Holokriiniset

Holokriiniset, also known as holocrine glands, are a type of exocrine gland characterized by the mode of secretion discharge. In holocrine secretion, the entire cell disintegrates to release its contents, which include the synthesized substances such as lipids, enzymes, or other complex molecules. This process results in the destruction of the secreting cell, which is replaced by new cells originating from underlying tissues.

Holocrine glands are found in various parts of the body, with the sebaceous glands of the skin being the most well-known example. Sebaceous glands produce sebum, an oily substance that lubricates and protects the skin and hair. During secretion, the gland's cells accumulate lipids, swell, and then rupture, releasing their contents. The cell debris and lipids form the secretion mass, and the gland continually regenerates new cells to replace those lost.

The holocrine mode contrasts with other secretion types such as merocrine (where cells release products via exocytosis without cell destruction) and apocrine (where a portion of the cell's apex is pinched off). The holocrine mechanism allows for the production and release of complex, lipid-rich secretions, often involved in protective or lubricative functions.

The secretion process in holocrine glands is generally regulated by hormonal or neural signals, depending on the gland type and location. These glands are essential for maintaining homeostasis, skin integrity, and defense mechanisms against external factors. The study of holocrine glands contributes to understanding various dermatological conditions and diseases related to gland dysfunction.