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Mammary Gland - Anatomy & Physiology (view source)
Revision as of 11:56, 3 September 2008
, 11:56, 3 September 2008no edit summary
{{toplink
|backcolour =EED2EE
|linkpage =Reproductive System - Anatomy & Physiology
|linktext =Reproductive System
|maplink = Reproductive System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
|sublink1=Reproductive System - Anatomy & Physiology#Lactation
= Introduction =
|subtext1=LACTATION
}}
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== Introduction ==
The mammary gland is a modified sweat gland that nourishes the young. It consists of the mamma and the teat. Undeveloped in both the male and female at birth, the female mammary gland begins to develop as a secondary sex characteristic at puberty. With the birth of the first young, and first lactation, the mammary gland attains its full size and function. When suckling by the young stops, milk production ceases and the gland regresses. Shortly before the next and subsequent parturitions, the gland is stimulated by hormonal changes to produce milk.
The mammary gland is a modified sweat gland that nourishes the young. It consists of the mamma and the teat. Undeveloped in both the male and female at birth, the female mammary gland begins to develop as a secondary sex characteristic at puberty. With the birth of the first young, and first lactation, the mammary gland attains its full size and function. When suckling by the young stops, milk production ceases and the gland regresses. Shortly before the next and subsequent parturitions, the gland is stimulated by hormonal changes to produce milk.
== Development of the Mammary Gland (prenatal mammogenesis) ==
= Development of the Mammary Gland (prenatal mammogenesis) =
* Mammary adipose tissue is derived from mesoderm. This is required for complete mammary development and is thus absent in the male. As a result, mammary development in the male is halted at the epidermal sprout stage.
* Mammary adipose tissue is derived from mesoderm. This is required for complete mammary development and is thus absent in the male. As a result, mammary development in the male is halted at the epidermal sprout stage.
== Structure ==
= Structure =
[[Image:Cow teat 4.jpg|thumb|right|150px|Dissection of a Teat of the Bovine Udder,Courtesy of Andrew Crook, Copyright RVC 2008]]
[[Image:Cow teat 4.jpg|thumb|right|150px|Dissection of a Teat of the Bovine Udder,Courtesy of Andrew Crook, Copyright RVC 2008]]
** '''Intermammary groove''': divides left and right rows of mammary complexes.
** '''Intermammary groove''': divides left and right rows of mammary complexes.
= Blood Supply =
== Blood Supply ==
== Arteries ==
=== Arteries ===
* In species with '''inguinal mammary glands''' (cow,ewe,goat,mare), the main blood supply is from the '''external pudendal artery'''. This arises indirectly from the external iliac artery via the femoral artery. The external pudendal artery passes through the inguinal canal.
* In species with '''inguinal mammary glands''' (cow,ewe,goat,mare), the main blood supply is from the '''external pudendal artery'''. This arises indirectly from the external iliac artery via the femoral artery. The external pudendal artery passes through the inguinal canal.
== Veins ==
=== Veins ===
* '''Thoracic mammary complexes''': drain into '''cranial superficial epigastric veins'''.
* '''Thoracic mammary complexes''': drain into '''cranial superficial epigastric veins'''.
* '''Abdominal and Inguinal mammary complexes''': drain into '''caudal superficial epigastric veins'''.
* '''Abdominal and Inguinal mammary complexes''': drain into '''caudal superficial epigastric veins'''.
** Open into '''external pudendal vein'''.
** Open into '''external pudendal vein'''.
== Innervation ==
= Innervation =
* '''Sympathetic''': Innervation to the blood vessels and teat sphincter smooth muscle via the '''genitofemoral nerve'''.
* '''Sympathetic''': Innervation to the blood vessels and teat sphincter smooth muscle via the '''genitofemoral nerve'''.
Mammary glands are mainly under the influence of endocrine hormones.
Mammary glands are mainly under the influence of endocrine hormones.
== Lymphatics ==
= Lymphatics =
* '''Inguinal mammary glands''': superficial inguinal lymph node
* '''Inguinal mammary glands''': superficial inguinal lymph node
* '''Thoracic mammary glands''': axillary lymph node
* '''Thoracic mammary glands''': axillary lymph node
=== Lymphatic drainage in the cow ===
== Lymphatic drainage in the cow ==
[[Image:Udder lymphatics.gif|thumb|right|150px|Lymphatic drainage of the udder, Copyright DeLaval 2008]]
[[Image:Udder lymphatics.gif|thumb|right|150px|Lymphatic drainage of the udder, Copyright DeLaval 2008]]
* '''Afferent lymphatic ducts''': pass dorsocaudal to reach the mammary lymph nodes (superficial inguinal).
* '''Afferent lymphatic ducts''': pass dorsocaudal to reach the mammary lymph nodes (superficial inguinal).
* '''Efferent lymphatic ducts''': pass into the abdomen through the inguinal canal to empty into the deep inguinal node.
* '''Efferent lymphatic ducts''': pass into the abdomen through the inguinal canal to empty into the deep inguinal node.
* '''Deep inguinal lymph node''': small, dorsocaudal udder. Too deep to be palpated.
* '''Deep inguinal lymph node''': small, dorsocaudal udder. Too deep to be palpated.
== Histology ==
= Histology =
* Secretory tissue is arranged into '''lobes''',each consisting of many '''lobules'''. Each lobule contains groups of '''alveoli''' (secretory compound tubuloalveolar cells) surrounded by a network of blood vessels and connective tissue stroma. The alveolar lumen is filled with milk during lactation.
* Secretory tissue is arranged into '''lobes''',each consisting of many '''lobules'''. Each lobule contains groups of '''alveoli''' (secretory compound tubuloalveolar cells) surrounded by a network of blood vessels and connective tissue stroma. The alveolar lumen is filled with milk during lactation.
== Species Differences ==
= Species Differences =
'''Position and Morphology'''
'''Position and Morphology'''