Exocrine gland

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Exocrine gland
Image:Dissected lactating breast gray1172.png
Dissection of a lactating breast. 1 - Fat 2 - Lactiferous duct/lobule 3 - Lobule 4 - Connective tissue 5 - Sinus of lactiferous duct 6 - Lactiferous duct
Image:Gray1033.png
Section of the human esophagus. Moderately magnified. The section is transverse and from near the middle of the gullet. a. Fibrous covering. b. Divided fibers of longitudinal muscular coat. c. Transverse muscular fibers. d. Submucous or areolar layer. e. Muscularis mucosae. f. Mucous membrane, with vessels and part of a lymphoid nodule. g. Stratified epithelial lining. h. Mucous gland. i. Gland duct. m’. Striated muscular fibers cut across.

Exocrine glands are glands that secrete their products into ducts. They are the counterparts to endocrine glands, which secrete their products directly into the bloodstream.

1 Examples
2 Types
3 External links

[edit] Examples

Typical exocrine glands include sweat glands, salivary glands, mammary glands, and many glands of the digestive system.

[edit] Types

There are multiple ways of classifying exocrine glands:

[edit] 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.

[edit] Method of secretion

Exocrine glands are named apocrine, holocrine gland, or merocrine gland based on how their product is secreted. In addition, people with cystic fibrosis usually have affected glands.

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.
Holocrine glands - the entire cell disintegrates to secrete its substance.
Merocrine glands - cells secrete their substances by exocytosis. Also called "eccrine."

[edit] 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.