Classification of epithelial tissue, structural features and classification of epithelial tissue

Structural characteristics of epithelial tissue: The main source of epithelial tissue is composed of a large number of dense fine white cells. Distributed in the body.

du extensive. There are no blood vessels in the epithelial tissue, but there are abundant nerve endings. Epithelial cells are polar, and polarity refers to certain differences in the structure and function of the epithelium or the two sides of the epithelial cell.

The cells of the epithelial tissue are adapted to their function and often differentiate to form a variety of special structures.

Classification of epithelial tissue: it can be divided into overlying epithelium, glandular epithelium, and sensory epithelium. According to the number of layers and morphology of the cell arrangement, the covered epithelium can be divided into single-layer flat epithelium, single-layer cubic epithelium, single-layer columnar epithelium, pseudostratified columnar ciliated epithelium, stratified flat epithelium and metastatic epithelium.

Features:1There are many cells, less interstitium, and the row is tight, bai

It is generally membranous. 2.Cells are polar, towards the lumen or body surface

surface, called free surface; The other side that is deep and connected to the connective tissue is called the basal surface, which is attached to the basal membrane. 3.Generally, there are no blood vessels and lymphatic vessels, and its nutrients are supplied by blood vessels in the deep connective tissue through the basal membrane. 4.There are abundant nerve endings.

There are four types of epithelial cells: unilamellar flat epithelium, monolamellar columnar epithelium, monostrapulous cubic epithelium, and pseudostratified columnar epithelium.

Epithelial tissue has the following characteristics:

The number of cells is high and the extracellular matrix is small.

Epithelial cells are polar and have one end facing the inner surface of the body surface or tubular structure, called the free surface; The other end is opposite to the free surface, called the basal surface, which is connected to the deep connective tissue by the basal membrane; The interface between the epithelial cells is lateral.

Most of the epithelial tissues are vascular, and the required nutrients are provided by the blood vessels in the connective tissue, which penetrate into the epithelial cell space through the basal membrane.

The epithelial tissue is composed of a dense nucleus with a small amount of interstitium, and there is a distinct complex of junctions between the lower cells. Generally, the cells are densely arranged into a membrane, covering the surface of the body and the surface of various organs, ducts, sacs and cavities in the body. Because the epithelial tissue is on the surface, it must have a face facing the outside world or cavity surface, which is called the free surface.

The other side is connected to the deep connective tissue by the basement membrane. It has characteristics due to the different structural differentiation of the free surface and the basal surface.

Covered epithelium: It is divided into monolayer epithelium and stratified epithelium, invertebrates are usually monolayered, higher animals are usually stratified, and the upper layers of gelatinization often fall off.

Glandular epithelium: composed of glandular cells, mostly a single layer of cubic epithelium.

Sensory epithelium: Specialized from epithelial cells with sensory functions, such as olfactory epithelium.

Epithelial tissue is characterized by an extremely large number of cells and few interstitiums; Epithelial cells are bipolar, one pole is called the free plane, towards the surface of the body or the cavity of the cavity organ, and the other pole is called the basal surface, towards the deep connective tissue; There are no blood vessels in the epithelial tissue, and the nutrients required depend on the blood vessels in the connective tissue to be supplied through the basal membrane.