Surface: Cells are irregular polygonal and nuclei are flat oval.

Section: The cells are flat and thin, with little cytoplasm and only the nuclear part is thicker.

Distribution: cardiovascular lymphatic lumen surface, pleural peritoneal pericardial surface, alveolar epithelium, renal cyst wall layer

Function: Conducive to the flow of fluids and material exchange and the activities of organs

Surface: Cells are hexagonal or polygonal

Section: The cells are cube-shaped with the nucleus in the center.

Distribution: Renal tubules, renal collecting tubules, thyroid follicles, retinal pigment epithelium

Function: secretion and absorption

Surface: Cells are hexagonal or polygonal

Section: The cells are columnar and the nuclei are oblong and mostly located at the base.

Distribution: gastrointestinal gall bladder, uterus, fallopian tube lumen

Function: Absorption and secretion

section

Composition: columnar, spindle, cone, goblet cells

Distribution: cavity surface of respiratory tract

Function: Secretion, protection and self-cleansing

section

Distribution: Keratinized: oral cavity, esophagus, vaginal surface, non-keratinized: surface of skin

Function: Friction resistance, prevention of foreign matter intrusion, regeneration and repair

Section: The deep layer is composed of several layers of polygonal cells, and the superficial layer is a layer of neatly arranged short columnar cells.

Distribution: Eyelid conjunctiva, male urethra, large ducts of some glands

section

Distribution: renal calyces, renal pelvis, ureters (urethra tube), bladder surface

Function: Prevent urine erosion

microvilli

cilia

Tight junctions/zonules of atresia: barrier function to prevent macromolecules from entering the intercellular space

Intermediate link/adhesive zonule: adhesion function to maintain cell shape and transmit cell contractility

Desmosomes: a very strong continuous pattern

Gap links: conduits that form direct communication between cells

When two or more exist in close proximity, it is called a junctional complex

Basement membrane: a film-like structure formed between the basal surface of epithelial cells and deep connective tissue

Plasma membrane infolding: the membrane on the basal surface of the epithelial cell folds inward toward the cytoplasm.

Hemidesmosomes: The connection between the basal surface of epithelial tissue and the basement membrane, fixing epithelial cells to the membrane