Sebaceous glands
These are associated with hair follicles and open into neck of hair follicle. In certain places of the body they occur independent of hair (e.g. glans penis, prepuce, labia vulvae, anus, external ear canal and tarsal glands of eyelids). Sebaceous glands are simple or branched alveolar, holocrine glands.
The alveolus has a basement membrane and is filed with epithelial cells. Of these, the one nearest periphery is smaller and cuboidal and the central ones are bigger and polygonal.
The fatty secretion (sebum) in the cytoplasm of cells is dissolved in ordinary preparations leaving honeycombed appearance. Ducts are lined by stratified squamous epithelium.
Sweat glands
- Two kinds of these are seen,
- Merocrine and
- Apocrine.
- The secretory portion of merocrine glands is a tubule rolled into a ball and lined by cuboidal epithelium (coiled tubular glands). The tubule has a basement membrane. The duct has a double layer of cuboidal cells with condensed, retractile borders.
- The secretory portion is located in dermis and duct passes between the dermal papillae to open, at the free surface of epidermis, at the sweat pore (Visible as minute pit to the naked eye).
- In the epidermis, the duct has no wall of pit to the naked eye). In the epidermis, the duct has no wall of its own but passes as spiral tunnel through the epithelium.
- The secretory portions of apocrine glands are very wide. They are also coiled tubular glands. Cytoplasm of the cell is basophilic, finely granular and contains fat droplets and pigment.
- The apical portion of cells detached into the lumen during secretion. The cells after discharge of secretion are lined with flattened nucleus.
- Ducts open into hair follicles above the sebaceous glands. There is one apocrine gland per hair follicle. The secretion is fatty.