Unit I

Sebaceous gland: It is seen on the side of the hair follicle towards which hair slants. Secretion is ofholocrine type. Basal cells resting on the basement membrane show mitosis. Newer cells are pushed fromthe inner layer towards the center of the gland. They synthesize sebum, a fatty material that accumulates inthe cytoplasm. As cells go further from nourishment they undergo necrosis releasing sebum.The gland is seen between the hair follicle and arrector pilorum muscle like a bunch of grapes.Cells are polyhedral containing fat, indicated by vacuolated cytoplasm. The duct is lined by stratifiedsquamous epithelium, which is continuous with the outer root sheath of the follicle. It is of simple branchedalveolar gland type. Duct of the sebaceous glands may usually open into the hair follicle but at places mayopen independent of hair follicle.Sweat gland: They are of two types: apocrine and merocrine.Apocrine sweat glands are seen in the axillaand in the groin. Sweat gland consists of a single long tube the lower end of which is highly coiled. Thecoiled part is called body of the gland and proximal uncoiled part is the duct. The duct follows a spiralcourse in the epidermis and opens on the surface as sweat pore.Because of coiled nature single gland is cut at various levels so that clusters of secretory units areseen and above that duct is also seen. The secretory units are lined by simple cuboidal epithelium with anarrow lumen. Secretory cells are covered from outer side by myoepithelial cells. Their nuclei can be seendeep to the nuclei of secretory cells. The duct is lined by stratified cuboidal epithelium.Notes:67