Editing Exocrine gland

{{short description|Gland that secretes substances onto an epithelial surface by way of a duct}}
{{Infobox anatomy
| Name        = Exocrine gland
| Latin       = glandula exocrina
| Image       = Centroacinar cells.jpg
| Caption     = An [[acinus]] is a round cluster of exocrine cells connected to a [[duct (anatomy)|duct]].
| Width       = 250px
| Image2      =
| Caption2    =
| Precursor   =
| System      =
| Artery      =
| Vein        =
| Nerve       =
| Lymph       =
}}

'''Exocrine glands''' are [[gland]]s that secrete substances onto an [[Epithelium|epithelial]] surface by way of a [[Duct (anatomy)|duct]].<ref name="wheater">{{cite book|title=Wheater's Functional Histology: A Text and Colour Atlas|last=Young|first=Barbara|last2=O'Dowd|first2=Geraldine|last3=Woodford|first3=Phillip|publisher=Elsevier|year=2013|isbn=978-0702047473|edition=Sixth|page=95|lccn=2013036824}}</ref> Examples of exocrine glands include [[sweat gland|sweat]], [[salivary]], [[mammary]], [[ceruminous]], [[lacrimal gland|lacrimal]], [[sebaceous]], [[prostate]] and [[mucous]]. Exocrine glands are one of two types of glands in the human body, the other being [[endocrine gland]]s, which secrete their products directly into the [[bloodstream]]. The [[liver]] and [[pancreas]] are both exocrine and endocrine glands; they are exocrine glands because they secrete products—[[bile]] and [[pancreatic juice]]—into the [[human gastrointestinal tract|gastrointestinal tract]] through a series of ducts, and endocrine because they secrete other substances directly into the bloodstream. Exocrine sweat glands are part of the integumentary system; they have eccrine and apocrine types.

==Classification==

===Structure===
Exocrine glands contain a glandular portion and a duct portion, the structures of which can be used to classify the gland.<ref name="wheater">{{cite book|title=Wheater's Functional Histology: A Text and Colour Atlas|last=Young|first=Barbara|last2=O'Dowd|first2=Geraldine|last3=Woodford|first3=Phillip|publisher=Elsevier|year=2013|isbn=978-0702047473|edition=Sixth|page=95|lccn=2013036824}}</ref>
* The duct portion may be branched (called compound) or unbranched (called simple).
* The glandular portion may be [[tubular gland|tubular]] or [[acinar gland|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===
Depending on how their products are secreted, exocrine glands are categorized as [[merocrine]], [[apocrine]], or [[holocrine]].<ref name="wheater" />
* [[Merocrine]] – the cells of the gland excrete their substances by [[exocytosis]] into a duct; for example, pancreatic acinar cells, [[eccrine sweat gland]]s{{dubious|date=November 2023}}, [[salivary gland]]s, [[goblet cell]]s, [[intestinal gland]]s, [[Lacrimal gland|tear glands]], etc.
* [[Apocrine]] – the apical portion of the [[cytoplasm]] in the [[cell membrane]], which contains the excretion, [[Budding|buds off]]. Examples are sweat glands of arm pits, pubic region, skin around anus, lips and nipples; [[mammary gland]]s, etc.
* [[Holocrine]] – the entire cell disintegrates to excrete its substance; for example, sebaceous glands of the [[skin]] and nose, [[meibomian gland]], [[Gland of Zeis|zeis gland]], etc.
<gallery mode=packed heights=100>
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
</gallery>

===Product secreted===
* [[Serous gland|Serous cell]]s secrete [[protein]]s, often [[enzyme]]s. Examples include [[gastric chief cell]]s and [[Paneth cell]]s
* [[Mucous gland|Mucous cell]]s secrete [[mucus]]. Examples include [[Brunner's gland]]s, [[esophageal gland]]s, and [[pyloric gland]]s
* Seromucous glands (mixed) secrete both protein and mucus. Examples include the [[salivary gland]]s: 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.
* [[Sebaceous gland]]s secrete [[Sebaceous gland#Sebum|sebum]], a lipid product. These glands are also known as oil glands, e.g. [[Fordyce spots]] and [[Meibomian glands]].

==Additional images==
<gallery>
File:Gray1033.png|Section of the human [[esophagus]].
File:Gray1172.png|Dissection of a lactating breast.
</gallery>

==See also==
{{Portal|Anatomy}}
* [[List of glands of the human body]]
* [[List of specialized glands within the human integumentary system]]

==References==
{{Reflist}}

==External links==
* [https://web.archive.org/web/20170426040555/http://www.mhhe.com/biosci/ap/histology_mh/glands.html Diagram at mhhe.com]

{{Epithelium and epithelial tissue}}
{{Authority control}}

[[Category:Exocrine system]]