Exocrine glands are that secrete substances onto an Epithelium surface by way of a duct.
Classification
Structure
Exocrine glands contain a glandular portion and a duct portion, the structures of which can be used to classify the gland.
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The duct portion may be branched (called compound) or unbranched (called simple).
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The glandular portion may be tubular gland or acinar gland, 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
Depending on how their products are secreted, exocrine glands are categorized as
merocrine,
apocrine, or
holocrine.
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Merocrine – the cells of the gland excrete their substances by exocytosis into a duct; for example, pancreatic acinar cells, eccrine sweat glands, , , , Lacrimal gland, etc.
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Apocrine – the apical portion of the cytoplasm in the cell membrane, which contains the excretion, Budding. Examples are sweat glands of arm pits, pubic region, skin around anus, lips and nipples; , etc.
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Holocrine – the entire cell disintegrates to excrete its substance; for example, sebaceous glands of the skin and nose, meibomian gland, zeis gland, etc.
File:405 Modes of Secretion by Glands Merocine.png|Merocrine secretion
File:405 Modes of Secretion by Glands Apocrine.png|Apocrine secretion
File:405 Modes of Secretion by Glands Holocrine.png|Holocrine secretion
Product secreted
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Serous gland secrete , often . Examples include gastric chief cells and
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Mucous gland secrete mucus. Examples include Brunner's glands, , and
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Seromucous glands (mixed) secrete both protein and mucus. Examples include the : although the parotid gland (saliva secretion 25%) is predominantly serous, the sublingual gland (saliva secretion 5%) mainly mucous gland, and the submandibular gland (saliva secretion 70%) is a mixed, mainly serous gland.
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secrete sebum, a lipid product. These glands are also known as oil glands, e.g. Fordyce spots and Meibomian glands.
==Additional images==
See also
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List of glands of the human body
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List of specialized glands within the human integumentary system
External links
