Gland - Types

Types

Glands can be divided into 2 groups:

  • Endocrine glands — are glands that secrete their products through the basal lamina into the blood stream and lack a duct system.
  • Exocrine glands — secrete their products through a duct or directly onto the apical surface, the glands in this group can be divided into three groups:
    • Apocrine glands — a portion of the secreting cell's body is lost during secretion. Apocrine gland is often used to refer to the apocrine sweat glands, however it is thought that apocrine sweat glands may not be true apocrine glands as they may not use the apocrine method of secretion.
    • Holocrine glands — the entire cell disintegrates to secrete its substances (e.g., sebaceous glands)
    • Merocrine glands — cells secrete their substances by exocytosis (e.g., mucous and serous glands). Also called "eccrine".

The type of secretory product of an Exocrine gland may also be one of three categories:

  • Serous glands — secrete a watery, often protein-rich product.
  • Mucous glands — secrete a viscous product, rich in carbohydrates (e.g., glycoproteins).
  • Sebaceous glands — secrete a lipid product.These glands are also known as oil glands.

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