Difference between revisions of "Lactation - Anatomy & Physiology"

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==Introduction==
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|linkpage =Reproductive System - Anatomy & Physiology
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|linktext =Reproductive System
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|maplink = Reproductive System (Content Map) - Anatomy & Physiology
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|pagetype =Anatomy
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|sublink1=Reproductive System - Anatomy & Physiology#Lactation
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|subtext1=LACTATION
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Mammary gland development is initiated prenatally in the female foetus and continues through puberty and pregnancy.  The anatomy and distribution of mammary glands is diverse among mammals.  Secretion of milk does not begin until shortly (hours) before parturition.  Lactation provides the neonate with the opportunity to  nurse and be nourished with minimal energy expenditure.  It also provides immunoprotection for the neonate because initial mammary secretions (colostrum) contain antibodies that provide passive immunity.  Lactation continues until the neonate is weaned.  After weaning, the mammary glands undergo involution and return to a non-secretory state.
 
Mammary gland development is initiated prenatally in the female foetus and continues through puberty and pregnancy.  The anatomy and distribution of mammary glands is diverse among mammals.  Secretion of milk does not begin until shortly (hours) before parturition.  Lactation provides the neonate with the opportunity to  nurse and be nourished with minimal energy expenditure.  It also provides immunoprotection for the neonate because initial mammary secretions (colostrum) contain antibodies that provide passive immunity.  Lactation continues until the neonate is weaned.  After weaning, the mammary glands undergo involution and return to a non-secretory state.
  
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== Key words ==
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''Key words''
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[[Image:Mammary Development.jpg|thumb|right|150px|Schematic Diagram to show the Stages of Mammary Development,Copyright RVC 2008]]
 
[[Image:Mammary Development.jpg|thumb|right|150px|Schematic Diagram to show the Stages of Mammary Development,Copyright RVC 2008]]
  
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* '''Milk ejection''': the expulsion of milk from alveoli
 
* '''Milk ejection''': the expulsion of milk from alveoli
 
* '''Involution''': termination of milk secretion and mammary gland regression.
 
* '''Involution''': termination of milk secretion and mammary gland regression.
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==Involution==
 
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* As the requirement for milk by the neonate decreases, suckling is less frequent.
 
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* Consequently, there is a buildup of pressure in the mammary gland causing secretory cells to become increasingly less functional - '''pressure atrophy'''.
 
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* Secretory cells then remain non-functional until a subsequent pregnancy, at which time prolactin, glucocorticoids and placental lactogen restimulate alveolar milk synthesis.
 
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* During involution, immune cells such as lymphocytes and macrophages invade the mammary tissue.  These produce immunoglobulins in the subsequent lactation.
 
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* Involution is critical to allow the replacement of senescent secretory cells which are lost by apoptosis.
 
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* In rodents, '''defoliation'''  occurs.  Secretory epithelial cells are sloughed from the basement membrane at involution.  Thus, more extensive regeneration is required at the onset of the subsequent lactation.
 
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==Associated Pathology==
 
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* Information on '''Hypocalcaemia 'Milk Fever'''' can be found [[General Pathology - Vascular Fluid Balance - Pathology#Calcium|here]]
 
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* Information on '''Mammary Neoplasia''' can be found [[Neoplasia - Pathology#Examples of Tumour Types|here]]
 
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* Information on '''Mastitis''' can be found [[Healing and Repair - Pathology#Female|here]]
 
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[[Category:Female Reproduction]]
 

Revision as of 12:38, 4 September 2008

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()Map REPRODUCTIVE SYSTEM (Map)
LACTATION



Mammary gland development is initiated prenatally in the female foetus and continues through puberty and pregnancy. The anatomy and distribution of mammary glands is diverse among mammals. Secretion of milk does not begin until shortly (hours) before parturition. Lactation provides the neonate with the opportunity to nurse and be nourished with minimal energy expenditure. It also provides immunoprotection for the neonate because initial mammary secretions (colostrum) contain antibodies that provide passive immunity. Lactation continues until the neonate is weaned. After weaning, the mammary glands undergo involution and return to a non-secretory state.


Key words

Schematic Diagram to show the Stages of Mammary Development,Copyright RVC 2008
  • Mammogenesis: the development of mammary tissue
  • Lactogenesis: the onset of milk secretion
  • Galactopoesis: the maintenance of lactation
  • Milk ejection: the expulsion of milk from alveoli
  • Involution: termination of milk secretion and mammary gland regression.
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