Glandular epithelium:
A)Presence or absence of ducts
•Exocrine – ducted
•Endocrine - ductless
B)Uni- or multicellular
C)Mode of secretion
D) Secretion products
Gland categories :
1) Exocrine - glands that exude secretions into a ductule system. Have two parts, acinous = secretory bulb and ductule.
2) Endocrine - glands exuding secretions directly into body fluids, ultimately blood.
3) Mixed - glands combining both the above characteristics (e.g. pancreas) in the same cell
Cellular composition :
1)Unicellular - single cell gland, Goblet cell; mucous secreting. GI tract, respiratory ducts. Secretion process alters cell and nucleus shape.
2) Multicellular -
a) intra epithelial gland - gland is entirely within a layer of epithelium. Common in pseudostratified columnar epithelium.
b) extra epithelial gland - in Connective Tissue below epithelium; may have different shapes; tubular and acinar
Modes of Secretion(how products leave the cell)
1) Merocrine - secretion does not affect the well-being of the cell = sweat glands.
2) Apocrine - small part of the cell cytoplasm is lost with the secretion; the cell is damaged but not killed = mammary glands.
3) Holocrine - great deal of cytoplasm is lost with the secretion; the cell dies.Sebaceous glands.
Secretion product
1) serous - thin, watery fluid, product of serous cells, small pink staining cuboidal cells with spherical to elliptical nuclei; salivary glands,sweat glands, pancreatic acinar
.2) mucous - thicker, viscous secretion, product of mucous cells, large blue staining cuboidal cells with flat, elongate nuclei; GI tract, oral cavity.
3) mixed serous-mucous - oral cavity, salivary.
4) sebaceous - thick, lipid rich secretions of cuboidal cells in certain skin regions - face, nose, axillary and pubic regions.
Myoepithelium:
Myoepithelium - specialized squamous epithelial cells with powers of contraction;
Surround glandular acini and ducts of many glands,
Contain actin, myosin, cytotokeratin =definitely epithelial in origin, not muscle...
