Glandular Epithelia
Glandular epithelia are formed by cells specialized to produce secretion the molecules to be secreted are generally stored in the cells in small membrane-bound vesicles called secretory vesiclesCalled secretor granules
Glands divided into: unicellular gland
Exocrine glands multi cellular gland
Endocrine gland two types of endocrine glands can be recognized based on the arrangement of their cells
The endocrine cells may form anastomosing cords interspersed between dilated blood capillaries e.g. Adrenal gland, parathyroid
The endocrine cells arrange as vesicles, follicles filled with non-cellular material. E.g.: thyroid gland
Exocrine gland classified into:
Simple gland: have only one unbranched duct compound gland have duct that branch repeatedly
Exocrine gland has
secretory portionducts
According to the number of cell, exocrine gland
Classified into:
Unicellular gland (goblet cell) : found in the living epithelium of small intestine and respiratory tract. The cytoplasm of the goblet cell filled with mucigen granules secreting: mucin (protein-polysaccharide)
Structure of exocrine gland
most glands are enclosed in a fibrous capsule, the capsule often gives off extensions called septa or trabecular that divide the gland into compartment called lobes, B.V, N. and the gland own ducts travel through those septa C.T of the gland called its stroma support and organizes the tissue . The cells that perform the tasks of synthesis and secretion called parenchyma these branches communicate with the secretory acini
According to the type of secretion
1. Mucous: secret a glycoprotein called mucin that mixes with water after it is secreted and forms the sticky product mucus .e.g. goblet cell
2. Serous cells: the acinar cells of the pancreas and parotid salivary glands are examples of serous cells between the nucleus and the free surface found a well-developed Golgi complex, several immature secretory granules derived from the Golgi complex, nature secretory granules formed after water is removed from the immature granules. The mature secretory granules accumulate in the apical cytoplasm. In cells that produce digestive enzymes (e.g. Pancreatic acinar cells), these granules are called
Zymogen granules. The granules stay in the apex until the cells is stimulated to secrete
3. Mixed contain both serous and mucus.
Methods of secretion
Merocrine (eccrine) this glands have secretory vesicles that release their secretion by exocytosis without loss of cytoplasm e.g. Tear gland, pancreas, gastric gland.
Holocrine glands: cells accumulate a product and then the entire cell fragments and the substance the cell had synthesized prior to its disintegration holocrine secretory tend to be thicker than merocrine secretion. e.g.: sebaceous gland.
Apocrine gland : the secretion was produced by bits of apical cytoplasm , breaking
A way from the cell. Secretory products discharged together with the apical cytoplasm.
E.g.: mammary gland, sweet gland.