Myoepithelium, with contractile function

Sensory epithelium, capable of sensing specific physical or chemical stimuli

Made up of a layer of flat cells

Observed from the surface of the epithelium, it is irregular or polygonal, the edges of the cells are jagged and chimeric, and the nucleus is oval and located in the center of the cell.

Observed from the vertical section, the cells are flat, with less cytoplasm, the nucleus-containing part is slightly thicker, and the nucleus is flat and oval.

endothelium, lining the lumen of the heart, blood vessels, or lymphatic vessels

Mesothelium: lines the surface of the pleura, peritoneum, and pericardium

Others: alveoli, renal capsule

The free surface is smooth, which can reduce friction between organs and facilitate the flow of blood and lymph and the penetration of materials.

Composed of a layer of approximately cubic cells

When viewed from the surface, cells appear polygonal or hexagonal.

Observed from the vertical section, the cells are roughly square in shape with round nuclei in the center.

Mainly distributed in renal tubules and thyroid gland

Has secretory and absorptive functions

Composed of a layer of columnar cells

Polygonal or hexagonal shape when viewed from cell surface

Observed from a vertical section, the cell is columnar, with an oval nucleus that is often located near the base of the cell, and its long axis is consistent with the long axis of the cell.

Distributed in organs such as gastrointestinal tract, gallbladder and uterus

Have secretory or absorptive function

There are scattered goblet cells between the single layer of columnar epithelial cells in the intestinal wall.

Composed of columnar cells, goblet cells, spindle cells and pyramidal cells, of which columnar cells are the most numerous and have a large number of cilia on the free surface.

The basal surface of all cells is attached to the basement membrane

Because the cells are of different heights, the nuclei are unevenly arranged on different horizontal planes. When viewed from a vertical section, they look like multiple layers, but are actually a single layer.

Mainly distributed in the respiratory tract and has a protective effect on the body

Made up of multiple layers of cells

Observed from the vertical section, the cells have different shapes

In the layer close to the basement membrane, basal cells are in the shape of short columns or cubes. They are stem cells with strong ability to proliferate and divide. Some new cells migrate to the shallow layer to replenish the shed cells.

The cells in the middle layers are polygonal and the cells are larger.

The superficial layers of cells are spindle-shaped or flat, and the flat cells on the surface have degenerated and gradually fallen off.

surface cells

The connection between the basal surface and the deep connective tissue is uneven and wavy, which increases the contact area between the two, making the connection stronger and ensuring the nutrient supply of the epithelial tissue.

Made up of several layers of cells

The cells in the surface layer are columnar and neatly arranged, the cells in the middle layers are polygonal, and the basal layer is short columnar cells.

Mainly distributed in the palpebral conjunctiva and male urethra, etc.

Composed of multiple layers of cells, which can be divided into surface cells, middle layer cells and basal cells

The shape and number of layers can change depending on the contraction and expansion state of the organ in which it is located.

The surface cells are larger, have rich cytoplasm, and often have double nuclei. They can cover several middle cells, called cover cells, which can prevent urine invasion and have a protective effect.

Distributed to renal pelvis, renal calyces, ureters and bladder

There are no ducts, and the secretions are hormones released around the cells or directly into the blood, such as the thyroid gland, adrenal glands, and pituitary glands.

Secretions are discharged through ducts to the body surface or into organ cavities, such as salivary glands, sebaceous glands, etc.

Mostly surrounded by a single layer of glandular cells with a cavity in the center

Directly connected to the secretory part and surrounded by single or stratified epithelium

The main function is to discharge secretions. Some catheters can also secrete or absorb water and electrolytes.

Most of them are pyramidal or columnar, with round nuclei and close to the base of the cells. The cells at the base are strongly basophilic, and the top cytoplasm is filled with eosinophilic zymogen granules.

Protein-secreting cells have the following ultrastructural characteristics

The regular distribution of protein-secreting cell organelles reflects the process of protein synthesis and secretion by gland cells.

secretion process

Most of them are cone-shaped or columnar. The cytoplasm at the top of the cell is filled with a large number of mucin granules. The nucleus is pressed to the base by the mucin granules, forming an oblate oval shape.

In H-E stained sections, except for a small amount of cytoplasm around the nucleus that is basophilic, the mucin granules are almost not stained, but appear in the shape of foam or vacuoles.

Goblet cells are scattered mucus cells that synthesize glycoproteins and then form secretory granules, which gather at the top of the cells and are released outside the cells through exocytosis.

acini composed of serous cells

acini composed of mucus cells

Composed of serous cells and mucus cells (mainly)