What is meant by the terms merocrine, apocrine and holocrine?
Give examples of each
Answers
Explanation:
Merocrine Gland- This is the gland in which secretory cells are secreted by the process of simple diffusion or exocytosis. In the secretion there is no destruction in the cytoplasm.
Examples- Goblet cells, tear gland, mucous gland, salivary gland etc.
Apocrine Gland- In it glands products which are secreted are collected into the apical part in the secretory cell and on apical portion which is also shed with the secretory matter.
Examples- Sweat Gland of armpit, mammary gland, sweat gland of lips, sweat gland of nipples etc.
Holocrine Gland- A huge destruction occurs in its produced secretion which is shed and secretory matter becomes more concentrated.
Examples- Sebaceous gland, Zeid gland , meibomian gland etc.
Answer:
Apocrine :-
Apocrine is a term used to classify exocrine glands in the study of histology. Cells which are classified as apocrine bud their secretions off through the plasma membrane producing extracellular membrane-bound vesicles. The apical portion of the secretory cell of the gland pinches off and enters the lumen. It loses part of its cytoplasm in their secretions. Apocrine glands are found primarily in the breast of lactating mammals.
Example :- Is the mammary glands, responsible for secreting milk.
Merocrine
Merocrine secretion Merocrine (or eccrine) is a term used to classify exocrine glands and their secretions in the study of histology. A cell is classified as merocrine if the secretions of that cell are excreted via exocytosis from secretory cells into an epithelial-walled duct or ducts and then onto a bodily surface or into the lumen.
Merocrine is the most common manner of secretion. The gland releases its product and no part of the gland is lost or damaged (compare holocrine and apocrine).
The term eccrine is specifically used to designate merocrine secretions from sweat glands (eccrine sweat glands)
Example :- Salivary gland
Holocrine
Holocrine is a term used to classify the mode of secretion in exocrine glands in the study of histology. Holocrine secretions are produced in the cytoplasm of the cell and released by the rupture of the plasma membrane, which destroys the cell and results in the secretion of the product into the lumen.
Holocrine gland secretion is the most damaging (to the cell itself and not to the host which begot the cell) type of secretion, with merocrine secretion being the least damaging and apocrine secretion falling in between.
Example :- sebaceous gland