Cells are irregular or polygonal

The nucleus is oval and located in the center of the cell

The edges of cells are jagged or wavy, and they are chimeric with each other.

Cells are flat and thin

Less cytoplasm

The core-containing part is slightly thicker

The surface is smooth, which is conducive to the flow of blood and lymph, and is conducive to the exchange of substances by endothelial cells.

Lining the lumen of the heart, blood vessels, and lymphatic vessels

The surface is moist and smooth, which can reduce friction in organ activities.

Distributed on the surface of pleura, peritoneum and pericardium

Cells are hexagonal or polygonal

Cells are cuboidal in shape with round nuclei in the center.

Cells are hexagonal or polygonal

The cells are columnar, the nucleus is oval, and its long axis is consistent with the long axis of the cell.

Shaped like a goblet, the bottom is narrow and contains darkly stained cores, and the top is enlarged and filled with particles

Mucin granules: contain PAS-positive mucin

After secretion, mucin combines with water to form mucus, which lubricates and protects the epithelium.

cells of different shapes

Deep: one or more layers of polygonal cells

Superficial part: a layer of neatly arranged short columnar cells

1. Surface cells (cover cells)

2. Middle layer cells

3. Basal cells

Empty bladder: the epithelium thickens, the number of cell layers increases, and the cover cells become large cuboids.

Full bladder: the epithelium becomes thinner, the number of cell layers decreases, and the cover cells become flat.

1. Secretory Department

2.Catheter

Function: Significantly increases the cell surface area, which is beneficial to the cell's absorption function

Function: Ability to swing rhythmically and directionally

Best method: Freeze etching replica method

Function: Block substances from passing through the intercellular space, acting as a barrier

Function: Adhesion, maintaining cell shape and transmitting cell contraction force

Function: Firm mechanical connection allows epithelium to withstand friction (skin, esophagus)

Connecting bodies: There are many regularly distributed columnar particles in the cell membrane at gap junctions.

The connectosome is surrounded by 6 rod-shaped connexin molecules and has a central lumen with a diameter of 2 nm.

Function: Generally, substances with a molecular weight less than 1500D, including ions, information molecules such as cAMP, amino acids, glucose, vitamins, etc., can circulate between adjacent cells, making extracellular nutrition metabolism, proliferation, differentiation, and functions unified (synchronized). change)

A thin film formed between the basal surface of epithelial cells and deep connective tissue

It is very thin and does not show color with HE staining, but the basement membrane in pseudostratified ciliated columnar epithelium and stratified squamous epithelium is thicker and appears pink, and appears black with silver-plated staining.

Close to the epithelium is the basal plate

Connected to connective tissue to form a mesh

Function

Mainly found in renal tubules

Function: Expands the surface area of ​​the cell base, which is conducive to the rapid transport of water and electrolytes

is half of the desmosome structure

Function: Fix epithelial cells to the basement membrane