Characteristic of epithelial tissue

Characteristics of the main types of fabrics

Lecture number 2.

In the human body allocate four main types of fabrics: epithelial, muscular, nervous and connecting.

Epithelial fabric - It consists of individual cells, and covers the surface of the body (for example, the skin) or the walls of the inner cavities, and also widespread the hollow organs (blood vessels and air vessels). There are two large groups of epithelial tissues (coating and iron), each of which, in turn, consists of several types.

According to the features of the cell location, two varieties of epithelial tissue-single-layer and multilayer epithelium are distinguished relative to each other. All epithelial cells single-layer epithelium Located in the basal membrane, homogeneous on the structure of the structure bonding them among themselves.

Single-layer epithelium Forms only one cell layer, and has three varieties:

Flat single-layer epithelium (consists of flat cells, lighter alveoli lines, the inner surface of the blood and lymphatic vessels is called endothelium).

Single-layer prismatic (cylindrical) epithelium consists of one cell layer, (it lines from the inside the ducts of most glands, gall-bubble, almost the entire digestive tract, where it includes glazing cells, as well as separate sections of the sex tract).

Classified epithelium - Wallows the walls of the air pathways and putty sinuses Nose (frontal, topless), brain ventricles. Cells have a prismatic form. At their free end there are thin hair-like processes - cilia. They are constant motion directed toward the outer opening of organs. IN respiratory tract They hinder dust, mucus and others foreign languages In the lungs.

Multilayer epithelium - consists of several cell layers (part of the cells does not have contact with the basal membrane). Consists of two zones: a) the zone of the orog (several layers of flat cells); b) Protective (basal zone) - consists of cylindrical cells.

Protective function - protects the fabrics located under it from damage and loss of fluid, and also prevents its intake in the body.

Secretor function - most glands and their ducts are formed by cylindrical (prismatic) epithelium.

Endocrine glands also consist of epithelial cells that firmly adjacent to each other or limit hollow bubbles (as in the thyroid gland).

Shell - Consisted from specialized cells and the backs of hollow organs and body cavities are lined. There are three types:

Mucous; All of them allocate fluid for lubrication or

Synovial; wetting the surface of the cavities they

Serous; covered.

Mucous– Out from the inside the wall of the organs of the digestive and urinary, as well as the air pathways. It consists of glassoid cells filled with mucous secrecy (consists of water, salts and a Muzin protein).

Sinovial shell - lins the cavities of the joints. It consists of gentle connective tissuecoated with one layer of flat endothelial cells. This shell highlights a synovial fluid that moisturizes and lubricates the articular surfaces, eliminating friction between them.

Serous shell - cover the walls of the abdominal and thoracic cavities, as well as located there internal organs. The lungs and walls of the chest cavity are covered pleverra.

Pericardiumdouble leaf covers the heart.

Peritoneum wipes organs and walls abdominal cavity. Plevra, Pericard and Peritonea - serous shells and have a number of common properties. Each of them consists of two smooth, brilliant leaflets that limit the cavity into which the liquid secreted by them. In composition, this serous liquid is very similar to the blood plasma or lymph. It reduces the friction between the organs and the circumsing walls of the cavities, contains antibodies, and also contributes to the removal of the exchange products in the lymphotock.

2.2 Muscle

Muscle - Designed for abbreviations, thanks to which a variety of human body movements are performed. It consists of a cylindrical form of muscle fibers corresponding to cells of other tissues. With the help of connective tissue, these fibers are combined into small beams.

Each type of fabric has many characteristic signs. They consist in the features of the structure, a set of functions performed, origin, the nature of the update mechanism. It is possible to characterize these fabrics in several criteria, but the most common is the morphofunctional affiliation. This classification of tissues makes it possible to most fully and significantly characterize each type. Depending on morphofunctional features, the following (cover), muscle muscular and nervous, distinguish.

Features Common Morphofunctional Signs

Epitheliums include a group of tissues widespread in the body. They may vary by origin, that is, to develop from ectoderma, mesoderm or entoderm, as well as perform different functions.

A list of common morphofunctional signs characteristic of all epithelial tissues:

1. Consist of cells called epithelocytes. Between them there are thin intermambrane gaps in which there is no in it, in turn, there is a test complex (glycocalix). It is through it that substances fall into the cells and they are out of cells through it.

2. The cells of epithelial tissues are located very tightly, which causes the formation of the formation. It is their presence that allows tissues to perform their functions. Methods for connecting cells between themselves can be different: with the help of des #, slot or dense contacts.

3. Connecting and epithelial fabrics that are located on the other, separates the basal membrane consisting of proteins and carbohydrates. Its thickness is 100 nm - 1 μm. There is no epithelium blood vesselsConsequently, their nutrition is diffuse, with the help of a basal membrane.

4. For epithelium cells, morphofunctional polarity is characteristic. They have a basal and apical pole. The core of epithelocytes is closer to the basal, and almost all of the cytoplasm is at apical. There may be accumulated cilia and microwaves.

5. Epithelial tissues are characterized by a well-pronounced ability to regenerate. They are characterized by the presence of stem, cambial and differentiated cells.

Various approaches to classification

From the point of view of the evolution of the cell of the epithelium formed earlier cells of other tissues. Their primary function was to eliminate the body from the external environment. At the present stage of evolution, epithelial tissues perform several functions in the body. According to this feature, such types of this tissue distinguish: cover, suction, excretory, secretory and others. The classification of epithelial tissues in morphological features takes into account the shape of the epithelocytes and the number of their layers in the formation. So, single-layer and multi-layered epithelial tissues.

Characteristics of single-layer single-row epithelium

The features of the structure of the epithelial tissue, which is customary to be called a single-layer, consist in the fact that the reservoir consists of a single cell layer. When the same height is characterized for all cells, then we are talking about a single-layer single-row epithelium. The height of epitheliocytes determines the subsequent classification according to which there is a presence in the body of a flat, cubic and cylindrical (prismatic) single-layer single-row epithelium.

Single-layer flat epithelium is localized in respiratory departments of light (alveoli), small ducts of glands, seeds, cavities of the middle ear, serous shells (mesothelium). It is formed from the mesoderm.

Places of localization of a single-layer cubic epithelium are grades and kidney tubes. The height and width of the cells are approximately the same, the kernels are rounded and are located in the center of the cells. The origin may be different.

Such a type of single-layer single-row epithelial tissue, as a cylindrical (prismatic) epithelium, is located in gastrointestinal, grades of glands, collective tubes of the kidneys. The height of the cells significantly exceeds the width. It has a different origin.

Characteristics of single-layer multi-seal fixed epithelium

If a single-layer epithelial tissue forms a reservoir of cells of different heights, then we are talking about the multi-row fibrillery epithelium. Such a fabric sweeps the surface of the air pathways and some sections of the sexual system (seeding paths and eggs) features of the structure of the epithelial tissue of this type consist in the fact that its cells are three types: short inserts, long faceted and glazing. All of them are located in one layer, but insert cells do not get to the top edge of the formation. When growing, they are differentiated and turn into eyelashed or glazing. The feature of the facet cells is the presence of a large number of cilia on the apical pole, the mucus is capable of producing.

Classification and structure of multilayer epithelium

Epithelium cells can form several layers. They are located on each other, therefore, direct contact with the basal membrane is available only at the deepestly located, basal layer of epithelocytes. It has stem and cambial cells. When they are differentiating, they are moving into the outdoor side. Criterion for further classification is the form of cells. So the multi-layered flat ornory, multilayer flat, non-illuminating and transitional epitheliums.

Characteristics of multilayer flat ornamental epithelium

It is formed from Etoderma. From this tissue consists of an epidermis, which is the surface layer of the skin, and the final portion of the rectum. The features of the structure of the epithelial tissue of this type are in the presence of five cells of the cells: basal, vicious, grain, brilliant and horn.

The basal layer is one series of high cylindrical cells. They are tightly connected with the basal membrane and have the ability to reproduce. The thickness of the hipged layer ranges from 4 to 8 rows of spinged cells. In the grain layer - 2-3 rows of cells. Epitheliocytes have a compiled shape, dense kernels. The brilliant layer is 2-3 rows of dying cells. The closest to the surface of the horny layer consists of a large number of rows (up to 100) of dead cells flat form. These are horny scales, in which there is a corne on Keratin.

The function of this tissue is to protect deeply lying tissues from external damage.

Features of the structure of a multi-layer flat non-propelled epithelium

It is formed from Etoderma. Localization places are cornea eyes, mouth cavity, esophagus and part of the stomach of some animal species. It has three layers: basal, hipgy and flat. The basal layer comes into contact with the basal membrane, consists of prismatic cells having large oval kernels, somewhat shifted to the apical pole. Cells of this layer, sharing, begin to extend upstairs. Thus, they cease to touch with the basal membrane and go into a hipgy layer. These are several layers of cells having an irregular polygonal shape and an oval kernel. The hipped layer passes into the surface - flat layer, the thickness of which is 2-3 cells.

Transitional epithelium

The classification of epithelial tissues provides for the presence of the so-called transition epithelium generated from the mesoderm. Localization places - ureters and bladder. Three layers of cells (basal, intermediate and coating) differ greatly in structure. For the basal layer, the presence of small cambial cells of different shapes lying on the basal membrane. In the intermediate layer, the cells are light and large, and the number of rows can be different. This directly depends on how much the organ is filled. In the coating layer of cells, multi-core, or polyploidy, is characterized, which is capable of distinguishing the mucus, which protects the surface of the formation from a detrimental contact with urine.

Irony epithelium

The characteristic of epithelial tissues was incomplete without a description of the structure and functions of the so-called glazed epithelium. This type of fabric is widespread in the body, its cells are able to produce and highlight special substances - secrets. The size, form, the structure of ferrous cells is very diverse, as the composition and specialization of secrets.

The process, during which the secrets are formed quite complicated, proceeds in several stages and is called a secretory cycle.

The features of the building of the epithelial tissue consisting of due to its purpose are determined. From this type of fabric, the formation of organs, the main function of which will be the development of the secret. These organs are customary to call the glands.

Epithelial fabricsor epithelium- Border fabrics, which are located on the border with an external environment, cover the surface of the body and mucous membranes of internal organs, lifted its cavities and form most glands.

The most important properties of epithelial fabrics:considered cell location (epithelocytes),forming layers, the presence of well-developed intercellular connections, location on basal membrane(a special structural education, which is between the epithelium and the loose fibrous connective tissue), the minimum amount of the intercellular substance,

border position in the body, polarity, high regeneration ability.

The main functions of epithelial tissues:barrier, protective, secretory, receptor.

The morphological features of the epithelialocytes are closely related to the function of cells and their position in the epithelial layer. In the form of epithelialocytes are divided into flat, cubicand column(Prismatic, or cylindrical). The epithelocyte core in most cells is relatively light (eukhromatin dominates) and large, in shape corresponds to the form of the cell. Epithelial cell cytoplasm usually contains well

1 There is no international histological terminology.

2 In the foreign literature, the term "syncytium" is usually denoted by symplastic structures, and the term "symplast" is practically not used.

developed organelles. In the cells of ferrous epithelium there is an active synthetic machine. The basal surface of epithelialocytes arrives to the baseal membrane, to which it is attached using hollowsmos- compounds similar to the structure with half the temples.

Basal membraneconnects the epithelium and subject to the connecting fabric; At the light-optical level on the preparations, it has the form of a structureless strip, is not colored by hematoxylin-eosin, but it is detected by silver salts and gives an intense chic reaction. At the ultrastructural level, two layers are found in it: (1) light plate (Lamina Lucida,or lamina Rara),adjacent to the plasmolem of the basal surface of epithelocytes, (2) dense plate (Lamina Densa),facing connective tissue. These layers differ in the content of proteins, glycoproteins and proteoglycans. Often describe another third layer - reticular plate (Lamina Reticularis),composing reticular fibrils, however, many authors consider it as a component of the connective tissue, which is not actually a basal membrane. The basal membrane contributes to maintaining normal architectonics, differentiation and polarization of the epithelium, ensures its durable bond with the connective tissue, performs selective filtration of nutrients entering the epithelium.

Intercellular compoundsor contacts,epitheliocytes (Fig. 30) are specialized areas on their lateral surface, which provide communication between cells with each other and contribute to the formation of the reservoirs, which serves as the most important distinctive feature of the organization of epithelial tissues.

(1)Dense (closing) connection Zonula Occludens)it is an area of \u200b\u200bpartial fusion of external sheets by plasmolm of two adjacent cells, blocking the propagation of substances from the intercellular space. It has a view of a belt surrounding the cell around the perimeter (at its apical pole) and consisting of anastomosing seewers intrambled particles.

(2)Desolation desmasmoma or adhesive belt (Zonula Adherens)localizes on the lateral surface of the epithelocyte, covering the cell around the perimeter in the form of a belt. Plasmolamm leaflets thickened from the inside in the connection area, the elements of the cytoskeleton are attached - actin microfilaments.The extended intercellular slot contains adhesive protein molecules (cadhelerins).

(3)Desmosoma, or spot of adhesion (Macula Adherens)consists of thickened disc part plasmolams of two adjacent cells (intracellular desmotomomous seals,or desmosomomomomomous plates),who serve as sites

plasmolamma intermediate Filaments (Tyophilaments)and separated by an extended intercellular gap containing adhesive protein molecules (desmocolly and desmogleins).

(4)Finger-shaped intercellular connection (Including) formed by the compounds of the cytoplasm of one cell, spent in the cytoplasm of the other, resulting in the strength of the cell connection with each other and increases the surface area through which intercellular metabolic processes can be carried out.

(5)Slotted or nexus (Nexus),formed by a combination of tubular transmembrane structures (Connexons),piercing plasmolemma of neighboring cells and connecting with each other in the region of narrow intercellular gap. Each Connexon consists of subunits formed by protein connexin, and is permeated by a narrow channel, which causes the free exchange of low molecular weight compounds between cells, providing their ionic and metabolic pairing. That is why slotted compounds refer to communication compounds,providing a chemical (metabolic, ion and electric) communication between epitheliocytes, in contrast to dense and intermediate compounds, despair and interfigitations that determine the mechanical communication of epithelocytes with each other and therefore referred to mechanical intercellular compounds.

The apical surface of epitheliocytes can be smooth, folded or contain cilia,and (or) microvili.

Types of epithelial fabrics:1) cover epithelium(form a variety of linings); 2) ferrous epitheliums(form glands); 3) sensory epithelium(Perform receptor functions, part of the senses).

Classification of epitheliumbased on two signs: (1) the structure that is determined by the function (morphological classification),and (2) sources of development in embryogenesis (Histogenetic classification).

Morphological classification of epithelium separates them depending on the number of layers in the epithelial formation and forms of cells (Fig. 31). By number of layersepitheliums are divided by single-layer(if all cells are located on the basement membrane) and multi-layered(If only one cell layer is located on the basal membrane). If all epithelium cells are associated with a basal membrane, but have different shapeand their kernels are located in several rows, then such an epithelium is called multi-row (pseudo-layer).By cell formepitheliums are divided by flat, cubicand column(Prismatic, cylindrical). In multilayer epitheliums under their form, they mean the shape of the cells of the surface layer. This classification

there are also some additional signs, in particular, the presence of special organelles (microwave, or brush, cuts and cilias) on the apical surface of the cells, their ability to delete (the last sign refers only to multilayer flat epitheliums). A special type of multi-layer epithelium, changing its structure, depending on the stretch, is found in the urinary tract and is called transition epithelium (a).

Histogenetic classification of epithelium aCAD has been developed. N. G. Chlopin and allocates five basic types of epithelium developing in embryogenesis from various tissue adventures.

1.Epidermal Typedeveloped from ectoderma and a precrowdal plate.

2.Enterodermal typedevelops from intestinal entoderma.

3.Tableprodermal typedevelops from a nuclear chipping and nephrotoma.

4.Angiodermal typeit develops from the Anchioblast (section of the mesenchym forming vascular endothelium).

5.Empendimoglyal typedeveloped from a nervous tube.

Cover epithelium

Single-layer flat epithelium it is formed by compressed cells with some thickening in the area of \u200b\u200bthe disk-forming kernel (Fig. 32 and 33). These cells are peculiar diplasmatic differentiation of cytoplasm,in which there is a more dense part located around the kernel (endoplasm),containing most of the organelle, and brighter outdoor part (ectoplasm)with low content of organelle. Due to the low thickness of the epithelial reservoir, the gases are easily diffusing through it and various metabolites are quickly transported. Examples of a single-layer flat epithelium serve the cavity cavity fever - mesothelium(see Fig. 32), vessels and hearts - endothelium(Fig. 147, 148); It forms the wall of some renal tubules (see Fig. 33), the lung alveol (Fig. 237, 238). The fattened cytoplasm of cells of this epithelium on transverse histological sections is usually traced with difficulty, only flattened kernels are clearly detected; A more complete picture of the structure of epithelocytes can be obtained on plane (film) preparations (see Fig. 32 and 147).

Single-layer cubic epithelium formed by cells containing the core of the spherical shape and the set of organelle, which are better developed than in the cells of the flat epithelium. Such an epithelium occurs in small collective kidney brainstuffs (see Fig. 33), renal

nalz (Fig. 250), in follicles thyroid gland (Fig. 171), in small pancreatic ducts, bile liver ducts.

Single-layer column epithelium (Prismatic, or cylindrical) is formed by cells with a pronounced polarity. The core of spherical, more often - the ellipsoid form is usually shifted to their basal part, and well-developed organogelles are unevenly distributed over the cytoplasm. Such an epithelium forms the wall of large collective kidney ducts (see Fig. 33), covers the surface of the gastric mucosa

(Fig. 204-206), guts (Fig. 34, 209-211, 213-215),

forms the dill of the gallbladder (Fig. 227), large bile ducts and pancreatic ducts, the uterine tube (Fig. 271) and the uterus (Fig. 273). For most of these epitheliums, the functions of secretion and (or) suction are characteristic. So, in the epithelium thin gut (see Fig. 34), there are two main types of differentiated cells - stated carbon cells,or enterocytes(provide private digestion and suction), and boxed cells,or box-shaped exocrinocytes(produce a mucus that performs a protective function). Suction is ensured by numerous microvills on the apical surface of enterocytes, the totality of which forms occaped (microvascular) Kam(See Fig. 35). Microwaves are covered with plasmolm, on top of which a layer of glycocalca is located, the basis forms a bunch of actin microfilaments, which is inserted into the cortical network of microfilaments.

Single-layer multi-row column camshot epithelium the most characteristic of the air paths is most characteristic (Fig. 36). It has cells (epithelocytes) of four main types: (1) basal, (2) inserts, (3) semicircles and (4) glazing.

Basal cellssmall sizes in their broad base are adjacent to the basement membrane, and the narrow apical part does not reach the lumen. They are cambial elements of the fabric providing its update, and, differentiating, gradually turn into insert cellswhich then give the beginning celebrateand box and shaped cells.The latter produce a mucus, which covers the surface of the epithelium, moving on it due to the bias of the ciliated cells. Separate and glazing cells are in contact with their narrow basal part with the basal membrane and are attached to inserted and basal cells, and apical - borders with the lumen of the organ.

Cilia- Organelles involved in the movement processes, in histological preparations have the form of subtle transparent increases on apical

the surface of the epithelocyte cytoplasm (see Fig. 36). When electron microscopy, it is found that their basis is a frame of microtubule (axonma,or axial thread), which is formed by nine peripheral doubles (pairs) of partially spilled microtubules and one centrally located pair (Fig. 37). Aksonia is connected by S. basal Telwhich lies at the base of the cilia, by its structure of identically centrioli and continues in strained root.The central pair of microtubule is surrounded central shell,from which the peripheral doubles diverge radial needles.Peripheral dubets are connected with each other nexic bridgesand interact with each other with dinaine handles.At the same time, neighboring dubls in the axone slide relative to each other, causing the cilia beat.

Multilayer flat ornamental epithelium it consists of five layers: (1) of basal, (2) vicious, (3) grain, (4) brilliant and (5) horny (Fig. 38).

Basal layerformed by cubic or columnar cells with basophilic cytoplasm, lying on the baseal membrane. This layer contains cambial elements of the epithelium and ensures the attachment of the epithelium to the subjectable tissue.

Hipgy layereducated by large cells of the wrong shape connected to each other by numerous processes - "spikes". During electron microscopy in the spikes area, desmosomoms are detected and the tone of the bundles of the tone. As it approaches the grain layer, the cells from the polygonal gradually become complicated.

Granular layer- relatively thin, formed by complicated (spindle-shaped) cells with a flat core and cytoplasma with large basophilic keratogial granules,containing one of the forerunners of the horn substance - Fillegary.

Brilliant layerit is expressed only in the epithelium of thick skin (epidermisis), covering palms and soles. It has the form of a narrow oxyphyl homogeneous strip and consists of flattened alive epithelial cells that turn into horny flakes.

Horny layer(The most superficial) has a maximum thickness of the skin epithelium (epidermis) in the field of palms and soles. It is formed by flat horny flakes with a sharply thickened plasmolym (shell) that are not contained by the kernel and organelle, dehydrated and filled with a horny matter. The latter at the ultrastructural level is represented by a network of thick beams of keratin filaments immersed in a dense matrix. Horny scales keep connections with each other

friend and held in the composition of the corneum layer thanks to partially saved desmosms; As it is destroyed by Desmosom in the outer parts of the flake layer, it is listed (deskvat) from the surface of the epithelium. Multilayer flat ornamental epithelium forms epidermis- Outer layer of skin (see Fig. 38, 177), covers the surface of some areas of the oral mucosa (Fig. 182).

Multi-layered flat non-propelled epithelium educated three layers of cells: (1) basal, (2) intermediate and (3) surface (Fig. 39). A deep part of the intermediate layer is sometimes distinguished as a parabaznaya layer.

Basal layerit has the same structure and performs the same functions as the same layer in a multilayer flat orinnoying epithelium.

Intermediate layerformed by large polygonal cells, which as approached the surface layer is applied.

Surface layerit is unarly separated from the intermediate and formed by compassionated cells, which the desquamation mechanism is constantly removed from the surface of the epithelium. Multi-layered flat-screw epithelium covers the surface of the cornea of \u200b\u200bthe eye (see Fig. 39, 135), conjunctivations, mucous membranes of the oral cavity (see Fig. 182, 183, 185, 187), pharynx, esophagus (Fig. 201, 202) , Vagina and vaginal part of the cervix (Fig. 274), parts of the urethra.

Transition epithelium (urged) - a special kind of multilayer epithelium, which lins most urinary tract - cups, lochanks, ureters and bladder (Fig. 40, 252, 253), part of the urethra. The shape of the cells of this epithelium and its thickness depends on the functional state (degree of stretching) of the organ. The transition epithelium is formed by three layers of cells: (1) basal, (2) intermediate and (3) surface (see Fig. 40).

Basal layerit is represented by small cells that their broad base are adjacent to the basal membrane.

Intermediate layerit consists of elongated cells, a narrower part of aimed to the basal layer and tile-shaped superimposed on each other.

Surface layerformed by large single-core polyploid or duidal surface (umbrella) cells, which mostly change their shape (from a round to flat) when tensile epithelium.

Ferrous epitheliums

Ferrous epitheliums form most iron- structures that perform a secretory function, producing and highlighting a variety of

products (secrets) providing various functions of the body.

Classification of ironbased on accounting of various signs.

According to the number of cells, the glands are divided into unicellic (for example, glazing cells, diffuse cells endocrine system) I. multicellular (Most glands).

By location (relative to the epithelial formation) allocate endoepithelial (lying within the epithelial formation) and exoepithelial (located outside the epithelial formation) gland. Most glands refer to exoepithelial.

At the place (direction) of the excretion of the gland shared on endocrine (distinguishing secretory products called hormones,in blood) and exocrine (Allocating secrets to the surface of the body or in the lumen of internal organs).

In exocryne glands, isolated (1) end (secretory) departments,which consist of ferrous cells producing secret, and (2) retreats,ensuring the release of synthesized products to the surface of the body or in the organ cavity.

Morphological classification of exocryne glandsbased on the structural signs of their terminal departments and output ducts.

In the form of end departments, the gland is divided into tubular and alveolar (spherical shape). The latter sometimes describe as well as acinuses. If there are two types of terminal glands are called tubularalveolar or tubular acinar.

On the branching of the end departments allocate unwanted and branched glands, on branching output ducts - simple (with a unbranched duct) and sophisticated (with branched ducts).

By chemical composition The stock produced gland is divided into protein (serous), mucous, mixed (protein-mucous) , Lipid, etc.

By the mechanism (method) of the removal of the secret (Fig. 41-46) allocate meroccins glands (secretion of the secret without disrupting the structure of the cell), apokrin (with separation in the secret of the apical cytoplasm of cells) and gololine (with full destruction of cells and the allocation of their fragments in the secret).

Frozen glands prevail in the human body; This type of secretion is well demonstrated by the example of the acinar cells of the pancreas - pancreatoocyte(See Fig. 41 and 42). The synthesis of the protein secret of acinar cells occurs

in the granular endoplasmic network located in the basal part of the cytoplasm (see Fig. 42), which is why this part on histological preparations is painted basophilic (see Fig. 41). Synthesis is completed in the Golgi complex, where secretory granules are formed, which accumulate in the apical part of the cell (see Fig. 42), caused its oxificial staining on histological preparations (see Fig. 41).

Apocryan glands in the human body are not a few; These include, for example, part of the sweat glands and the mammary glands (see Fig. 43, 44, 279).

In the lactating breast, the terminal departments (alveoli) are formed by ferrous cells (Galactocytes),in the apical part of which large lipid drops are accumulated, separated into the lumen along with small areas of the cytoplasm. This process is clearly traced in electron microscopy (see Fig. 44), as well as at the light-optical level using histochemical methods for detecting lipids (see Fig. 43).

Gollycrew glands in the human body are represented by the only species - silent glands of the skin (see Fig. 45 and 46, as well as Fig. 181). In the terminal department of such a gland having a view glandular bagyou can trace the division of small peripheral basal(Cambigual) cellstheir offset to the center of the bag with filling lipid inclusions and transformation into sebocytes.Sebocytes acquire View vacuoleted degenerating cells:their core is wrinkled (subjected to picnosis), the cytoplasm is overwhelmed with lipids, and the plasmolm at the final stages is destroyed with the allocation of cellular content that generates the secret of the gland - sebum.

Secretor cycle.The secretion process in glandular cells flows cyclically and includes serial phases that can partially overlap. The most common secretory cycle of the exocrine glandular cell producing a protein secret, which includes (1) phase of the absorptionsource substances (2) phase synthesissecret, (3) phase accumulationsynthesized product and (4) phase allocation of secret(Fig. 47). In the endocrine glandular cell, synthesizing and highlighting steroid hormones, a secretory cycle has some features (Fig. 48): after phases of absorptionsource materials follow phase depositin the cytoplasm of lipid droplets containing a substrate for the synthesis of steroid hormones, and after phase synthesisthe accumulation of the secret in the form of granules does not occur, the synthesized molecules immediately stand out from the cell of the diffusion mechanisms.

Epithelial fabrics

Cover epithelium

Fig. 30. Scheme of intercellular compounds in the epitheliums:

A - area of \u200b\u200bthe location of the intercellular compounds complex (highlighted by frame):

1- epithelithelocyte: 1.1 - apical surface, 1.2 - lateral surface, 1.2.1 - Complex of the intercellular compounds, 1.2.2 - Palpid compounds (interdigate), 1.3 - basal surface;

2-basal membrane.

B - type of intercellular compounds on ultra-thin cuts (reconstruction):

1 - dense (closing) connection; 2 - a desious desams (adhesive belt); 3 - desmasms; 4 - slotted connection (NEXUS).

B - three-dimensional scheme of the structure of intercellular connections:

1 - dense compound: 1.1 - intramaterial particles; 2 - Singing desmasmoma (adhesive belt): 2.1 - Microfilaments, 2.2 - Intercellular adhesive proteins; 3 - Desmosoma: 3.1 - desmosomomous plate (intracellular desplain seal), 3.2 - Tonophylants, 3.3 - Intercellular adhesive proteins; 4 - slotted connection (Nexus): 4.1 - Connexions

Fig. 31. Morphological classification of epithelium:

1 - single-layer flat epithelium; 2 - single-layer cubic epithelium; 3 - single-layer (single-row) column (prismatic) epithelium; 4, 5 - single-layer multi-row (pseudo-layer) column epithelium; 6 - multi-layered flat non-propelled epithelium; 7 - multilayer cubic epithelium; 8 - multilayer column epithelium; 9 - multilayer flat ornamental epithelium; 10 - Transition Epithelium (Breeding)

The arrow shows the basal membrane

Fig. 32. Single-layer flat epithelium (mesothelium peritoneum):

A - plane preparation

Color: nitric acid silver hematoxiline

1 - borders of epithelocytes; 2 - epithelial cell cytoplasm: 2.1 - endoplasm, 2.2 - ectoplasm; 3 - epithelial core; 4 - Double Cell

B - layout of the structure on the cut:

1 - epithelial cell; 2 - Basal membrane

Fig. 33. Single-layer flat, cubic and columnal (prismatic) epithelium (kidney brainstuff)

Color: Hematoksilin-Eosin

1 - single-layer flat epithelium; 2 - single-layer cubic epithelium; 3 - single-layer column epithelium; 4 - connecting tissue; 5 - Blood vessel

Fig. 34. Single-layer columnary cut (microwave) epithelium (small intestine)

Coloring: Iron Hematoxylin Mudskin

1 - Epithelium: 1.1 - columid cut (microwave) epithelitelocyte (enterocyte), 1.1.1 - a worn (microvortogenic) Kaimka, 1.2 - a glass-shaped exocrinocyte; 2 - basal membrane; 3 - loose fibrous connecting fabric

Fig. 35. Microvascular cells of intestinal epithelium (ultrastructure scheme):

A - longitudinal sections of microvones; B - transverse sections of microvones:

1 - plasmolem; 2 - glycocalix; 3 - a beam of actin microfilaments; 4 - Cortical network of microfilaments

Fig. 36. Single-layer multi-row column selection (flickering) epithelium (trachea)

Coloring: Hematoxylin-eosin Mudskin

1 - Epithelium: 1.1 - Classified Epithelitelocyte, 1.1.1 - Cilia, 1.2 - Boxed Excrinocyte, 1.3 - Basal epithelilate, 1.4 - insert epitheliocyte; 2 - basal membrane; 3 - loose fibrous connecting fabric

Fig. 37. Ciller (ultrastructure scheme):

A - longitudinal cut:

1 - Cilicry: 1.1 - Plasmolm, 1.2 - microtubule; 2 - Basal Taurus: 2.1 - Satellite (Center for the organization of microtubule); 3 - Basal Fur

B - transverse cut:

1 - plasmolem; 2 - Duples of microtubule; 3 - a central pair of microtubule; 4 - dinaine handles; 5 - nonxine bridges; 6 - radial needles; 7 - Central shell

Fig. 38. Multilayer flat ornamental epithelium (epidermis thick skin)

Color: Hematoksilin-Eosin

1 - Epithelium: 1.1 - basal layer, 1.2 - hipped layer, 1.3 - grain layer, 1.4 - brilliant layer, 1.5 - horny layer; 2 - basal membrane; 3 - loose fibrous connecting fabric

Fig. 39. Multi-layered flat non-propelled epithelium (cornea)

Color: Hematoksilin-Eosin

Fig. 40. Transitional epithelium - urobes (bladder, ureter)

Color: Hematoksilin-Eosin

1 - Epithelium: 1.1 - Basal layer, 1.2 - Intermediate layer, 1.3 - Surface layer; 2 - basal membrane; 3 - loose fibrous connecting fabric

Ferrous epitheliums

Fig. 41. Furrine Secrecy Type

(End Division of the Pancreas - Azinus)

Color: Hematoksilin-Eosin

1 - secretory (acinar) cells - pancreatation: 1.1 - kernel, 1.2 - the basophilic zone of the cytoplasm, 1.3 - the oxyphyl zone of cytoplasm with secrets of the secret; 2 - Basal membrane

Fig. 42. Ultrastructural organization of ferrous cells with a murface type of secretion (section of the terminal area of \u200b\u200bthe pancreas - acinus)

Figure with EMF

1 - secretory (acinar) cells - pancreatation: 1.1 - kernel, 1.2 - granular endoplasmic network, 1.3 - Golgi complex, 1.4 - Secret granules; 2 - Basal membrane

Fig. 43. APOCRIN TYPE OF STRUCTION (Alveola lactating breast)

Color: Sudan black hematoksilin

1 - secretory cells (galactocytes): 1.1 - kernel, 1.2 - lipid drops; 1.3 - apical part with a section of cytoplasm separated from it; 2 - Basal membrane

Fig. 44. Ultrastructural organization of ferrous cells with apocryne type of secretion (section of the Alveola lactating breast)

Figure with EMF

1 - secretory cells (galactocytes): 1.1 - kernel; 1.2 - Lipid drops; 1.3 - apical part with a section of cytoplasm separated from it; 2 - Basal membrane

Fig. 45. Holocreen style of secretion (silent skin of the skin)

Color: Hematoksilin-Eosin

1 - gland cells (sebocytes): 1.1 - basal (cambial) cells, 1.2 - gland cells different stages transform into secret, 2 - the secret of the gland; 3 - basal membrane

Fig. 46. \u200b\u200bUltrastructural organization of ferrous cells at a holocrine type of secretion (plot song gland skin)

Figure with EMF

1-cells of the gland (sebocytes): 1.1 - basal (cambial) cell, 1.2 - gland cells at different stages of conversion to secret, 1.2.1 - lipid drops in cytoplasm, 1.2.2 - kernels undergoing picnosis;

2- Secret of the gland; 3 - basal membrane

Fig. 47. Structural and functional organization of the exocrine glandular cell in the process of synthesis and selection of protein secret

Scheme by EMF

BUT - phase of the absorption phase Synthesis Secretprovided by the granular endoplasmic network (2) and the Golgie complex (3); IN - phase accumulation of secretin the form of secretory granules (4); G - phase allocation of the secretthrough the apical surface of the cell (5) into the lumen of the terminal department (6). The energy required to provide all these processes is produced by numerous mitochondria (7)

Fig. 48. Structural and functional organization of the endocrine glandular cell in the process of synthesis and selection of steroid hormones

Scheme by EMF

BUT - phase of the absorptionthe base of the source substances that are brought by blood and is transported through the basal membrane (1); B - phase depositin the cytoplasm of lipid droplets (2) containing a substrate (cholesterol) for the synthesis of steroid hormones; IN - synthesis phasesteroid hormone is provided by a smooth endoplasmic network (3) and mitochondria with tubular-vesicular crystamines (4); G - phase allocation of the secretthrough the basal surface of the cell and the wall of the blood vessel (5) into the blood. The energy required to provide all these processes is produced by numerous mitochondria (4)

The sequence of processes (phases) is shown in red arrows

Epithelial cloth-- This is a fabric, lining the surface of the skin, cornea of \u200b\u200bthe eye, serous shells, the inner surface of the hollow organs of the digestive, respiratory and urogenital system, as well as the forming gland.

Epithelial tissue is characterized by a high regeneration capacity. Different types Epithelial tissue perform different functions and therefore have a different structure. Thus, the epithelial tissue that performs mainly the function of protection and separation from the external environment (skin epithelium) is always multi-layered, and some kinds are equipped with a stratum and participate in protein metabolism. Epithelial tissue, in which the function of external exchange is the leading (intestinal epithelium), always single layer; It has microwaves (brush kaym), which increases the suction surface of the cell. This epithelium is also a ferrous, highlighting a special secret necessary to protect epithelial tissue and chemical treatment of substances penetrating through it.

The kidney and nominal types of epithelial tissue perform the functions of suction, the formation of secrets, phagocytosis; They are also single-layer, one of them is equipped with a brush border, the other has pronounced recesses, on the basal surface. In addition, some epithelial tissue have permanent narrow intercellular gaps (renal epithelium) or periodically arising large intercellular holes - shomates (non-epithelium), which contributes to the filtering and suction processes. The cells of the epithelial tissue are covered with a plasma shell surface and contain organides in the cytoplasm. In cells through which exchange products are intensified, the plasma shell of the basal part of the cell body is folded. On the surface of a series of cells, the epithelium of the cytoplasm forms small, traversed the dudder to grow - microwaves. On the surface of the epithelium of some organs (trachea, bronchi, etc.) there are cilia.

Based on this, it can be understood that there are many types of epithelium, which can be submitted in the following classification.

Morphofunctional classification It takes into account the features of the structure and the functions of the functions of one or another type of epithelium. (Table 1)

The structure of the epithelium is divided into single-layer and multi-layered. The main principle of this classification is the ratio of cells to the basal membrane. The functional specificity of single-layer epithelium is usually determined by the presence of specialized organelles. So, for example, in the stomach epithelium single-layer, prismatic, single-row iron. The first three definitions characterize the characteristics of the structure, and the latter - indicates that the stomach epithelocytes perform a secretory function. In the intestines of the epithelium single-layer, prismatic, single-row catalyne. The presence of a brush drive in epithelocytes implies a suction function. In the aerial paths, in particular in the trachea, the epithelium is one-layer, prismatic, multi-row (or flicker). It is known that the cilia in this case plays a protective function. Multilayer epitheliums perform protective and ferocular functions.

Table 1. Comparative characteristics of the epithelium

ONTOFLOGENTIC CLASSIFICATION (N. G. Chlopin). This classification takes into account, one or another epithelium has developed from which embelling. According to this classification, the epidermal (skin), enterodermal (intestinal), purposefrodermal, ependimoglyal and angiodermal types of epitheliums are distinguished.

So, for example, skin-type epithelium covers the skin, lifts purph cavity, esophagus, vagina, urethra, border department of the anal canal; Epithelium of the intestinal type sweeps a single-chamber stomach, a schuch, intestines; The epithelium of the pricklyfrodermal type lins the body cavity (the mesothelium of serous shells), forms the kidney channels; Empindimoglyal type of epithelium lins the stomach brain and central canal spinal cord; Anchodermal epithelium lifts the cavity of the heart and blood vessels.

For single-layer and multi-layer epitheliums, it is characteristic of the presence of a special organelle - des #, semi-mosmos, tonophylamans and tonofibrils. In addition, single-layer epitheliums may have on the free surface of cilia cells and microwaves.

All types of epithelium are located on the basal membrane. The basal membrane consists of fibrillar structures and an amorphous matrix containing complex proteins - glycoproteins, proteoglycans and polysaccharides (glycosaminoglycans).

The basal membrane carries out the regulation of the permeability of substances (barrier and trophic function), prevents the invasion of the epithelium into the connective tissue. The glycoproteins (fibronectin and laminin) contained in it contribute to the adhesion of epithelocytes to the membrane and induce their proliferation and differentiation in the process of regeneration.

By location and the functions of the epithelium are divided into: surface (cover organs outside and inside) and ferrous (form secretory departments and output flows of exocryne glands).

Surface epitheliums are border tissues that separate the body from the external environment and participate in the metabolism and energy between the body and the external environment. They are located on the surface of the body (cover), mucous membranes of internal organs (stomach, intestines, lungs, hearts, etc.) and secondary cavities (lining).

Irony epitheliums have pronounced secretory activity. Breed cells - glandulocytes are characterized by the polar arrangement of the organization of the total value, well-developed EPS and the Golgie complex, the presence of secretory granules in the cytoplasm.

Process functional activity The glandular cells associated with the formation, accumulation and allocation of the secret beyond its limits, as well as the recovery of the cell after the secretion of the secret, is called a secretory cycle. Epithelial Fabric Organic Regenerator

In the process of a secretory cycle in glandulocytes from the blood, the original products (water, various inorganic substances and low molecular weight organic compounds are received: amino acids, monosaccharides, fatty acid et al.), Of which, with the participation of the whole value, the secret is synthesized and accumulated in cells, and then the exocytosis is released into an external or internal environment.

The secretion of the secret (extrusion) is carried out by diffusion or in the form of granules, but can also turn the entire cell into the overall secretory mass.

Regulation of the secretory cycle is carried out with the participation of humoral and nerve mechanisms.

Epithelial fabric - the outer surface of the skin of a person, as well as the lining surface of the mucous membranes of internal organs, the gastrointestinal, lungs, most yellowing.

The epithelium is deprived of blood vessels, so the power is due to the adjacent connective tissues that feed from blood flow.

Epithelial fabric functions

Basic function Skin epithelial tissue - protective, that is, limiting the impact of external factors on internal organs. The epithelial tissue has a multi-layer structure, so the oroging (dead) cells are rapidly replaced by new ones. It is known that the epithelial tissue has elevated regenerating properties, which is why the human skin is rapidly updated.

There is also an intestinal epithelial tissue with a single-layer structure, which has suction properties, due to which digestion occurs. In addition, the intestinal epithelium has a property of selection of chemicals, in particular sulfuric acid.

Epithelial man fabric Covers almost all organs from the cornea of \u200b\u200bthe eye, to the respiratory and urogenital system. Some types of epithelial tissue are involved in protein and gas exchange.

The structure of the epithelial tissue

The cells of the single-layer epithelium are located on the basement membrane and form one layer with it. The cells of the multilayer epithelium are formed from several layers and only the lowest layer is the basal membrane.

In the form of structure, the epithelial fabric is: cubic, flat, cylindrical, eyelash, transitional, iron, etc.

Reliable epithelial fabric It has secretory functions, that is, the ability to allocate the secret. Irony epithelium is located in the intestine, makes sweat and salivary glands, inland secretion glands, etc.

The role of epithelial tissue in the human body

Epithelium plays a barrier role, protecting internal fabrics, and also contributes to the absorption of nutrients. When drinking hot food, part of the intestinal epithelium dies and completely restored overnight.

Connective tissue

Connective tissue - Construction matter, uniting and filling the entire organism.

The connecting tissue is presented in nature at once in several states: liquid, gel, solid and fibrous.

Accordingly, blood and lymph, fat and cartilage, bones, ligaments and tendons, as well as various intermediate fluids of the body are distinguished. The feature of the connective tissue is that the intercellular substance in it is much larger than the cells themselves.

Types of connective tissue

— Cartilage, It happens three types:
a) hyaline cartilage;
b) elastic;
c) fibrous.

— Bone (consists of forming cells - osteoblast and destructive - osteoclast);

— FibrousIn turn, it happens:
a) loose (creates a framework for organs);
b) decorated dense (forms tendons and ligaments);
c) Unformed dense (the superior and perception is built from it).

— Trophic (blood and lymph);

— Specialized:
a) reticular (almonds are formed from it, bone marrow, lymph nodes, kidneys and liver);
b) fatty (subcutaneous energy reservoir, heat regulator);
c) pigmented (rainbow shell of the eye, halo of nipples, anus circle);
d) Intermediate (synovial, spinal and other auxiliary fluids).

Functions of connective tissue

These features of the structure allow connective tissue to perform various functions:

1. Mechanical (reference) The function is performed by bone and cartilage tissue, as well as fibrous connecting tissue of tendons;
2. Protective The function performs a fatty tissue;
3. Transportationthe function is performed by liquid connective tissues: blood and lymph.

Blood provides the transfer of oxygen and carbon dioxide, nutrients, metabolic products. Thus, the junction tissue connects parts of the body among themselves.

Connective fabric structure

Most of the connective tissue is an intercellular matrix of collagen and non-body proteins.

In addition to it, naturally cells, as well as a series of fibrous structures. SAME important cells Fibroblasts can be called, which produce substances of the intercellular fluid (elastin, collagen, etc.).

Independent in the structure are also basophiles (immune function), macrophages (fighters of pathogenic organisms) and melanocytes (responsible for pigmentation).