How Do Exocrine Glands Release Their Secretory Products?

00:01 It is important to understand how glands release their secretory products and I said earlier in this lecture, we are going to concentrate only on exocrine glands. Well, there are three ways. In this diagram, there are three representations of the way in which exocrine glands or secretory cells secrete their products. Firstly, there is merocrine secretion. Now this secretion, this form of secretion, this mechanism of secretion is probably the most common. The secretory cells make their products and they store their products within little membrane-bound granules at the apex of the cell. And when they stimulate to secrete, these little granules containing the secretory product moves to the apical surface of the cell, the membrane fuses with the cell membrane and the product is released into the luminal space by a process we call exocytosis. So that's merocrine secretion.

01:20 Another way in which the cell gets rid of these products is by apocrine secretion. Apocrine secretion is where often the secretion product is stored at the apical surface, but then the apical surface or a component of that apical surface breaks off and so what is released into the luminal space is the secretion product that also is a small part of the cytoplasm of the cell. And this is common in some of the glands in the eyelid and probably in the mammary gland. And the remaining form of secretion, the remaining way in which cells release a product is called holocrine secretion. This is where the cell synthesize its product, accumulates the product within the cell cytoplasm, but then undergoes programmed cell death.

02:21 So the whole cell is lost into the luminal space. Holocrine secretion, we will see when we look at skin, when we look at the sebaceous gland in skin where holocrine secretion occurs.