Exocrine gland
Exocrine glands are glands that secrete
substances on to an epithelial surface by
way of a duct.[1] Examples of exocrine
glands include sweat, salivary, mammary,
ceruminous, lacrimal, sebaceous, prostate
and mucous. Exocrine glands are one of
two types of glands in the human body, the
other being endocrine glands, 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 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.
Exocrine gland
An acinus is a round cluster of exocrine cells
connected to a duct.
Details
Identifiers
Latin
glandula exocrina
MeSH
D005088 (https://mes
hb.nlm.nih.gov/recor
d/ui?ui=D005088)
TH
H2.00.02.0.03014 (htt
ps://www4.unifr.ch/if
aa/Public/EntryPage/
PDF/TH%20Chapter%
20H2.00.pdf)
9596 (https://bioporta
FMA
l.bioontology.org/onto
logies/FMA/?p=class
es&conceptid=http%3
A%2F%2Fpurl.org%2F
sig%2Font%2Ffma%2
Ffma9596)
Anatomical terminology
Classification
Structure
Exocrine glands contain a glandular
portion and a duct portion, the structures
of which can be used to classify the
gland.[1]
The duct portion may be branched
(called compound) or unbranched
(called simple).
The glandular portion may be tubular or
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
glands, holocrine glands, or merocrine
glands based on how their products are
secreted.[1]
Merocrine secretion – cells excrete their
substances by exocytosis into a duct;
for example, pancreatic acinar cells,
maximum sweat glands of humans,
salivary glands, goblet cells, intestinal
glands, tear glands, etc.
Apocrine secretion – apical portion of
the cytoplasm in the cell membrane that
contains the excretion buds off.
Examples are sweat glands of arm pits,
pubic region, skin around anus, lips and
nipples; mammary glands, etc.
Holocrine secretion – the entire cell
disintegrates to excrete its substance;
for example, sebaceous glands of the
skin and nose, meibomian gland, zeis
gland, etc.
Product secreted
Serous cells secrete proteins, often
enzymes. Examples include gastric
chief cells and Paneth cells
Mucous cells secrete mucus. Examples
include Brunner's glands, esophageal
glands, and pyloric glands
Seromucous glands (mixed) secrete
both protein and mucus. Examples
include the salivary glands: 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 glands secrete sebum, a
lipid product. These glands are also
known as oil glands, e.g. Fordyce spots
and Meibomian glands.
Additional images