excrete perspiration through the pores in the skin; "Exercise makes one sweat" (同)sudate, perspire
condensation of moisture on a cold surface; "the cold glasses were streaked with sweat"
any of various organs that synthesize substances needed by the body and release it through ducts or directly into the bloodstream (同)secretory organ, secretor, secreter
(of exocrine glands) producing a secretion in which part of the secreting cell is released with the secretion; "mothers milk is one apocrine secretion"
An apocrine sweat gland (/ˈæpəkrən, -ˌkraɪn, -ˌkriːn/; from Greek apo– "away" and krinein "to separate")[5][6] is composed of a coiled secretory portion located at the junction of the dermis and subcutaneous fat, from which a straight portion inserts and secretes into the infundibular portion of the hair follicle.[7] In humans, apocrine sweat glands are found only in certain locations of the body: the axillae (armpits), areola and nipples of the breast, ear canal, eyelids, wings of the nostril, perianal region, and some parts of the external genitalia.[8] Modified apocrine glands include the ciliary glands in the eyelids; the ceruminous glands, which produce ear wax; and the mammary glands, which produce milk.[3] The rest of the body is covered by eccrine sweat glands.[9]
Most non-primate mammals, however, have apocrine sweat glands over the greater part of their body.[8] Domestic animals such as dogs and cats have apocrine glands at each hair follicle but eccrine glands only in foot pads and snout. Their apocrine glands, like those in humans, produce an odorless, oily, opaque secretion[10] that gains its characteristic odor upon bacterial decomposition.[11] Eccrine glands on their paws increase friction and prevent them from slipping when fleeing from danger.[12]
Contents
1Structure
2Sweating
2.1Mechanism
3Prevalence
4See also
5References
5.1Citations
5.2Sources
6External links
Structure
The apocrine gland is made up of a glomerulus of secretory tubules and an excretory duct that opens into a hair follicle;[13] on occasion, an excretory duct opens to the skin surface next to the hair.[14] The gland is large and spongy, located in the subcutaneous fat deep in the dermis,[9][15] and has a larger overall structure and lumen diameter than the eccrine sweat gland.[16][8] The secretory tubules of apocrine glands are single layered, but unlike the eccrine secretory tubules, contain only a single type of ductal epithelial cell,[17] varying in diameter according to their location, and sometimes branching off into multiple ducts. The tubules are wrapped in myoepithelial cells, which are more developed than in their eccrine gland counterparts.[18][19]
Sweating
In hoofed animals and marsupials, apocrine glands act as the main thermoregulator, secreting watery sweat.[9] For most mammals, however, apocrine sweat glands secrete an oily (and eventually smelly) compound that acts as a pheromone,[20] territorial marker, and warning signal.[10][21][22] Being sensitive to adrenaline, apocrine sweat glands are involved in emotional sweating in humans (induced by anxiety, stress, fear, sexual stimulation, and pain).[21]
In a five-month-old human fetus, apocrine glands are distributed all over the body; after a few weeks, they exist in only restricted areas,[9] including the armpits and external genitalia.[8] They are inactive until stimulated by hormonal changes in puberty.[21]
Mechanism
The apocrine gland secretes an oily fluid with proteins, lipids, and steroids that is odorless before microbial activity. It appears on the skin surface mixed with sebum, as sebaceous glands open into the same hair follicle.[23] Unlike eccrine sweat glands, which secrete continuously, the apocrine glands secrete in periodic spurts.[20]
Apocrine sweat glands were originally thought to use only apocrine secretion: vesicles pinch off from the secretory cells, then degrade in the secretory lumen, releasing their product.[24] More recent research has also shown that merocrine secretion takes place.[25]
Myoepithelial cells form a smooth muscle lining around the secretory cells; when the muscles contract, they squeeze the secretory ducts and push out the accumulated fluid into the hair follicle.[20][26] Sweat and sebum are mixed in the hair follicle and arrive mixed at the epidermal surface.[9] The apocrine sweat is cloudy, viscous, initially odorless, and at a pH of 6–7.5. It contains water, protein, carbohydrate waste material, and NaCl.[27] The sweat only attains its characteristic odor upon being degraded by bacteria, which releases volatile odor molecules.[23] More bacteria (especially corynebacteria) leads to stronger odor. The presence of axillary hair also makes the odor even more pungent, as secretions, debris, keratin, and bacteria accumulate on the hairs.[15]
Prevalence
Non-primate mammals usually have apocrine sweat glands over most of their bodies.[8] Horses use them as a thermoregulatory device, as they are regulated by adrenaline and more widely distributed on equines than in other groups.[28] Skunks, on the other hand, use the glands to release a secretion that acts as a powerful defense mechanism.[20]
The "axillary organs", limited regions with equal numbers of apocrine and eccrine sweat glands, only exist in humans, gorillas, and chimpanzees.[9] In humans, the apocrine glands in this region are the most developed (with the most complex glomeruli).[18] Men have more apocrine sweat glands than women in all axillary regions.[29][30]
East Asians who have nearly complete loss of typical body odor, when compared to people of African and European descent, have significantly less of the characteristic axillary odorants and variants in the ABCC11 gene, which is expressed and localized in apocrine sweat glands.[31] Racial differences also exist in the cerumen glands, apocrine sweat glands which produce earwax.[3] East Asians have predominantly dry earwax, as opposed to sticky; the gene encoding for this is strongly linked to reduced body odor, whereas those with wet, sticky earwax (Africans and Europeans) are prone to more body odor.[32]
See also
Eccrine sweat gland
Exocrine gland
Sebaceous gland
Secretory gland
References
Citations
^Federative International Committee on Anatomical Terminology (2008). Terminologia histologica: international terms for human cytology and histology. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. p. 121. ISBN 9780781775373.
^Neas, John F. "Development of the Integumentary System". In Martini, Frederic H.; Timmons, Michael J.; Tallitsch, Bob. Embryology Atlas (4th ed.). Benjamin Cumings. Retrieved 17 December 2012.
^ abcKrstic 2004, p. 466.
^Tsai 2006, p. 496.
^McKean, Erin (2005). "apocrine". The New Oxford American Dictionary (2 ed.). ISBN 9780195170771.
^McKean, Erin (2005). "apo-". The New Oxford American Dictionary (2 ed.). ISBN 9780195170771.
^Elston, William D.; James, Timothy G.; Berger, Dirk M. (2006). Andrew's Diseases of the Skin: Clinical Dermatology (10th ed.). Philadelphia: Saunders Elsevier. p. 7. ISBN 9780808923510.
^ abcdeKurosumi, Shibasaki & Ito 1984, p. 255.
^ abcdefEdgar Folk Jr, G.; Semken Jr, A. (1 September 1991). "The evolution of sweat glands". International Journal of Biometeorology. 35 (3): 181. doi:10.1007/BF01049065. ISSN 0020-7128.
^ ab"Cutaneous Apocrine Gland Tumors". The Merck Veterinary Manual. Merck Sharp & Dohme Corp. Archived from the original on 2016-03-04.
^Eroschenko 2008, pp. 228–229.
^Wilke et al. 2007, p. 170.
^Kurosumi, Shibasaki & Ito 1984, pp. 255–256.
^Tsai 2006, pp. 496–497.
^ abTsai 2006, p. 497.
^Krstic 2004, p. 468.
^Bolognia, Jean; Jorizzo, Joseph L.; Schaffer, Julie V. (2012). Dermatology. Structure and Function of Eccrine, Apocrine and Sebaceous Glands (3rd ed.). pp. 539–544. ISBN 978-0723435716.
^ abKurosumi, Shibasaki & Ito 1984, p. 256.
^Eroschenko 2008, p. 226.
^ abcdSpearman, Richard Ian Campbell (1973). The Integument: A Textbook For Skin Biology. Biological Structure and Function Books. 3. CUP Archive. p. 137. ISBN 9780521200486.
^ abcWilke et al. 2007, p. 171.
^Jordania, Joseph (2011). Why do People Sing? Music in Human Evolution. Tbilisi, Georgia: Logos. pp. 123–124. ISBN 9789941401862.
^ abWilke et al. 2007, p. 175.
^"sweat gland". Miller-Keane Encyclopedia & Dictionary of Medicine, Nursing, and Allied Health (7th ed.). Saunders. 2003. Retrieved 18 December 2012.
^Henrikson, Ray C.; Kaye, Gordon I.; Mazurkiewicz, Joseph E. (1 July 1997). NMS Histology (3rd ed.). Lippincott Williams & Wilkins. p. 234. ISBN 9780683062250.
^Martini, Frederic. Anatomy and Physiology' 2007. Rex Bookstore, Inc. p. 122. ISBN 9789712348075.
^Draelos, Zoe Diana (2010). "Prevention of Cosmetic Problems". In Norman, R. A. Preventitive Dermatology. Springer. p. 182. doi:10.1007/978-1-84996-021-2_16. ISBN 9781849960267.
^Caceci, Thomas. "Integument I: Skin". VM8054 Veterinary Histology Laboratory Exercises. Virginia–Maryland Regional College of Veterinary Medicine. Archived from the original on 13 May 2015. Retrieved 19 December 2012.
^Wilke et al. 2007, p. 174.
^Stoddart 1990, p. 60.
^Preti, & Leyden 2010, p. 344.
^Nakano, Motoi; Miwa, Nobutomo; Hirano, Akiyoshi; Yoshiura, Koh-ichiro; Niikawa, Norio (1 January 2009). "A strong association of axillary osmidrosis with the wet earwax type determined by genotyping of the ABCC11 gene". BMC Genetics. 10 (1): 42. doi:10.1186/1471-2156-10-42. PMC 2731057. PMID 19650936.
Sources
Eroschenko, Victor P. (2008). "Integumentary System". DiFiore's Atlas of Histology with Functional Correlations. Lippincott Williams & Wilkins. pp. 212–234. ISBN 9780781770576.
Krstic, Radivoj V. (18 March 2004). Human Microscopic Anatomy: An Atlas for Students of Medicine and Biology. Springer. pp. 464, 466–469. ISBN 9783540536666.
Kurosumi, Kazumasa; Shibasaki, Susumu; Ito, Toshiho (1984). "Cytology of the Secretion in Mammalian Sweat Glands". In Bourne, Geoffrey H.; Danielli, James F. Protein Diffusion in Cell Membranes: Some Biological Implications. Orlando, Florida: Academic Press. pp. 253–330. ISBN 9780123644879.
Stoddart, D. Michael (1990). The scented ape: The biology and culture of human odour. Cambridge: Cambridge University Press. pp. 60–61. ISBN 978-0521375115.
Tsai, Ren-Yu (1 January 2006). "Treatment of Excessive Axillary Sweat Syndrome (Hyperhidrosis, Osmidrosis, Bromhidrosis) with Liposuction". In Shiffman, Melvin A.; Di Giuseppe, Alberto. Liposuction: Non-Cosmetic Applications. Germany: Springer. pp. 496–497. ISBN 9783540280439.
Wilke, K.; Martin, A.; Terstegen, L.; Biel, S. S. (June 2007). "A short history of sweat gland biology". International Journal of Cosmetic Science. 29 (3): 169–179. doi:10.1111/j.1467-2494.2007.00387.x. ISSN 1468-2494. PMID 18489347.
Preti, George; Leyden, James (2010). "Genetic Influence on Human Body Odor: From Genes to the Axillae". Journal of Investigative Dermatology. 130: 334–345. doi:10.1038/j.2009.396 (inactive 2019-03-05).
External links
Diagram of eccrine and apocrine sweat glands from Mayo Clinic
v
t
e
Skin and related structures
Skin
Epidermis
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale
Basement membrane
Basal keratinocyte
Lamina lucida
Lamina densa
Dermis
Papillary
Dermal papillae
Reticular
Subcutaneous tissue
Panniculus/Pannus (Panniculus adiposus
Panniculus carnosus)
Membranous layer
Loose connective tissue
Superficial fascia
Adnexa
Skin glands
Sweat glands: Apocrine sweat gland
Eccrine sweat gland
Sebaceous
Hair
Root sheath
Outer root sheath
Inner root sheath
Henle's layer
Huxley's layer
Hair shaft
Cuticle
Cortex
Medulla
Bulb with matrix cells
Hair follicle
Muscle
Arrector pili muscle
Pilosebaceous unit
Hair sebaceous gland
Nail
Nail matrix
Nail plate
Lunula
Eponychium
Paronychium
Hyponychium
Authority control
TH: H3.12.00.3.03002
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