Each Type Of Epithelial Cells

Simple Squamous

Single layer of flat cells with disc- shaped central nuclei and sparse cytoplasm, the simplest epithelium. They allow for passage of materials by diffusion and filtration in sites where protection is not important, secretes lubricating substances in serosae. Kidney glomeruli; air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; lining of ventral body cavity.

Simple cuboidal

Single layer of cubelike cells with large spherical central nuclei. Secretion and absorption, Kidney tubules, ducts and secretory portions of small glands, ovary surface.

Simple columnar

Single layer of tall cells with round oval nuclei, some cells bear cilia layer may contain mucus-secreting unicellular glands. Absorption secretion of mucus enzymes and other substances, ciliated type propels mucus or reproductive cells by ciliary action Non-ciliated type lines most of the digestive tract (stomach and anal canal), gallbladder, and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus.

Pseudostratified

Single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels may contain mucus-secreting cells and bear cilia. Secretion, particularly of mucus; propulsion of mucus by ciliary action. Nonciliated type in male’s sperm-carrying ducts and ducts of large glands; ciliated variety lines the trachea, most of the upper respiratory tract.

Stratified squamous

Thick membrane composed of several layers basal cells are cuboidal or columnar and metabolically active surface cells are flattened; in the keratinized type the surface cells are full of eratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers. Protects underlying tissues in areas subjected to abrasion. Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin a dry membrane.

Transitional

Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar, surface cells dome shaped or squamous like depending on degree of organ stretch. Stretches readily and permits distension of urinary organ by contained urine. Lines the ureters, urinary bladder. and part of the urethra.