Desmosome is present in epithelial tissue.They consist of thickned area and several fine tonofibrils extending from each plasma membrane into cytoplasm of respective cells. Macula adherens is a kind of desmosome.e.g., Vagina,Urinary bladder.
At place,the adjacent cells form ion-rich gap junctions for intercellular communication and chemical exchange.These junctions probably do not provide physical support.
These are interwoven finger-like processes of plasma membrane of adjacent cells.
These are minute projections that arise from adjacent cell membranes.The intercellular bridge make contact with one another.
Function of Epithelial tissue
Epithelial tissue have a wide spread distribution throughout the body and serve several important functions-
(1) Generalized protection is the most important function of membranous epithelium. It is the relatively tough and impermeable epithelial covering of the skin that protects the body from mechanical and chemical injury and also from invading bacteria and other disease causing micro-organisms.
(2) Epithelial structures specialized for sensory functions are found in the skin,nose,eye and ear.
(3) Glandular epithelium is specialized for secretory acitvity,secretory products include hormones, mucous,digestive juices and sweat.
(4)The epithelium lining of the gut and respiratory tracts allows the absorption of nutrients from gut.
(5)It is the specialized epithelial lining of kidney tubules that makes the excretion and concentration of excretory products in the urine.
(6) Ciliated epithelium moves fluid ,mucus and other materials in the organs it lines.
(7) Germinal epithelium of the seminiferous tubules and ovaries produces spermatozoa and ova respectively.
(8) The ability of epithelium to regenerate quickly helps in the healing of wounds.
(9)Pigmented epithelium of retina darkens the cavity of eyeball.
(10)The epithelia check the absorption of harmful or unnecessory materials.
(11)Epithelium of alveoli of the lungs brings about exchange of gases between blood and air.
(12) Epithelium also produce exoskeletal strucutures such as scales,feathers,hair ,nail,claws ,horns and hoofs.