Exocrine glands

Exocrine glands are glands that secrete their products (enzymes) into ducts (duct glands). They are the counterparts to endocrine glands, which secrete their products (hormones) directly into the bloodstream (ductless glands).

Examples
Typical exocrine glands include sweat glands, salivary glands, mammary glands, stomach, liver and the pancreas.

Types
There are multiple ways of classifying exocrine glands:

Structure
Exocrine glands contain a glandular portion and a duct portion, the structures of which can be used to classify the gland.
 * The duct portion may be branched (called compound) or unbranched (called simple).
 * The glandular portion may be tubular, acinar, or may be a mix of the two (called tubuloacinar). If the glandular portion branches, then the gland is called a branched gland.

Method of secretion
Exocrine glands are named apocrine gland, holocrine gland, or merocrine gland based on how their product is secreted.


 * Apocrine glands - a portion of the plasma membrane buds off the cell, containing the secretion. Apocrine gland is often used to refer to the apocrine sweat glands which use merocrine secretion.
 * Holocrine glands - the entire cell disintegrates to secrete its substance.
 * Merocrine glands - cells secrete their substances by exocytosis. Also called "eccrine."

Product secreted

 * Serous cells secrete proteins, often enzymes. Examples include chief cells and Paneth cells
 * Mucous cells secrete mucus. Examples include Brunner's glands, esophageal glands, and pyloric glands
 * Mixed glands secrete both protein and mucus. Examples include the salivary glands, although parotid gland is predominantly serous, and sublingual gland is predominantly mucous.

List of exocrine glands
Glands typically may be referred to by two or more means, though some terms are rarely seen. The names of the anatomists who first described them are often employed, as: