Difference between revisions of "Avian Male Reproductive Tract - Anatomy & Physiology"

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== Introduction ==
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<big><center>[[Reproductive System|'''BACK TO REPRODUCTIVE SYSTEM''']]</center></big>
  
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Paired reproductive tracts lie along the dorsal body wall.  Each tract consists of a testis, a rudimentary epididymis and a highly convoluted deferent duct running alongside the ureter.  The testes are connected to the body wall by a mesochorium.  This peritoneal fold serves as an attachment for the testes and also a conduit for nerves and blood vessels.
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<big><center>[[Reproductive_System#Exotics|'''BACK TO EXOTICS''']]</center></big>
  
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== Testes ==
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<big><center>[[Exotics_-_Avian_Reproductive_Anatomy_and_Physiology_-_Anatomy_%26_Physiology|'''BACK TO AVIAN REPRODUCTIVE ANATOMY & PHYSIOLOGY''']]</center></big>
  
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[[Image:Chicken male dissection.jpg|thumb|right|150px|Dissection of the Male Avian Reproductive Tract- Courtesy of Andrew Crook, Copyright RVC 2008]]
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<big><center>[[Exotics_-_Reproduction_in_the_Male_Avian_-_Anatomy_%26_Physiology|'''BACK TO MALE AVIAN REPRODUCTIVE ANATOMY & PHYSIOLOGY''']]</center></big>
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= Testes =
  
 
* Bean-shaped, paired
 
* Bean-shaped, paired
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* Medially, they lie close to the aorta and caudal vena cava.
 
* Medially, they lie close to the aorta and caudal vena cava.
 
* Each testical suspended by a short '''mesochorium''' and surrounded medially by the abdominal air sac.
 
* Each testical suspended by a short '''mesochorium''' and surrounded medially by the abdominal air sac.
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* Left tends to be larger than right in immature birds.
 
* Left tends to be larger than right in immature birds.
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* Dimensions increase rapidly with sexual activity.
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* Dimentions increase rapidly with sexual activity.
 
* In the non-breeding season, testes shrink to almost nothing and become hard to visualize.
 
* In the non-breeding season, testes shrink to almost nothing and become hard to visualize.
 
* Dormant testes light brown/yellow in colour, turn white when sexually active.
 
* Dormant testes light brown/yellow in colour, turn white when sexually active.
 
** In some psittacine species, immature or dormant testes may appear black due to melanocytes located in the interstitium.
 
** In some psittacine species, immature or dormant testes may appear black due to melanocytes located in the interstitium.
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* '''Semniferous tubules''' produce '''sperm''' from the epithelium.
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* Interstitial '''Leydig cells''' lie between semniferous tubules.
 
* Tunical Albiguinea thinner than in mammals.
 
* Tunical Albiguinea thinner than in mammals.
 
* '''No Pampiniform plexus'''.
 
* '''No Pampiniform plexus'''.
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* '''Epididymis is small and can be considered absent'''.  '''Sperm maturation occurs in the Vas Deferens'''.
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* Vas Deferens closely associated with the Ureter in the dorsomedial midline coelom, distinguished by its zig-zag appearance.
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* Vas Deferens enters dorsal wall of the Urodeum.
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* No [[Male_Reproductive_Tract_-Accessory_Sex_Glands_-_Anatomy_%26_Physiology|accessory sex glands]].
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= Phallus =
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* Convoluted '''semniferous tubules''' comprised of '''spermatogonia''' (germ cells) and '''Sertoli cells''' make up the bulk of the testes.  These are responsible for '''spermatogenesis'''.
 
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* '''Interstitial Leydig cells''' produce male androgens.
 
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* Mature spermatozoa exit into the '''rete testes''', which connects to the cranial '''epididymis'''.
 
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** Rete testes not present in all birds.
 
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** Epididymis considered vestigial in birds.
 
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*** Sperm maturation occurs in the '''ductus deferens'''.
 
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* Epididymis lies along the dorsomedial aspect of the testes.
 
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* Spermatazoa exit the epididymis and enter the ductus deferens.
 
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** Ductus deferens is closely associated with the Ureter in the dorsomedial midline coelom, distinguished by its zig-zag appearance.
 
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** Under hormonal control, more convoluted in the breeding season.
 
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* Ductus deferens enters the dorsal wall of the '''cloacal urodeum'''.
 
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** Straightens and abruptly widens at ats junction with the cloaca.
 
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*** Structure known as the '''receptacle''' in Passerines and Budgerigars.
 
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*** Receptacle appears bean-shaped when engorged with semen.
 
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*** Birds that do not have the receptacle structure have little sperm storage capacity.
 
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== Phallus ==
 
  
 
* Most birds lack a true phallus.
 
* Most birds lack a true phallus.
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* Analogue of the mammalian penis.
 
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* Consists of a small median tubercle flanked by a pair of large, lateral phallic bodies.
 
 
* When present, the avian phallus is soley reproductive and becomes engorged by lymph fluid instead of blood during erection.
 
* When present, the avian phallus is soley reproductive and becomes engorged by lymph fluid instead of blood during erection.
 
* Owing to the lack of accessory sex glands, avian semen has low volume.
 
* Owing to the lack of accessory sex glands, avian semen has low volume.
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=== Absence of Phallus ===
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== Absence of Phallus ==
  
 
* Psittacines, Passerines, Pidgeons and birds of prey all have no phallus.
 
* Psittacines, Passerines, Pidgeons and birds of prey all have no phallus.
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* Copulate by transferring semen from the everted [[Avian_Vent_and_Cloaca_- Anatomy & Physiology#The_Cloaca|Cloaca]] directly into the female [[Avian Female Reproductive System#Oviduct|oviduct]].
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* Copulate by transferring semen from the everted [[The_Avian_Vent_and_Cloaca_-_Anatomy_%26_Physiology#The_Cloaca|Cloaca]] directly into the female [[Exotics_-_Anatomy_of_the_Female_Reproductive_System_-_Anatomy_%26_Physiology#Oviduct|oviduct]].
  
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=== Non-Protrusible Phallus ===
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== Non-Protrusible Phallus ==
  
 
* Rudimentary non-protrusible phallus is seen in male Turkeys and Chickens.
 
* Rudimentary non-protrusible phallus is seen in male Turkeys and Chickens.
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* Consists of a small medial tubercle intimately associated on each side with lymphatic folds and vessels.
 
* Consists of a small medial tubercle intimately associated on each side with lymphatic folds and vessels.
 
* When erect with lymph, the phallus develops a median groove.
 
* When erect with lymph, the phallus develops a median groove.
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** Median groove permits passage of ejaculate down into the everted female [[Avian Female Reproductive System#Oviduct|oviduct]].
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** Median groove permits passage of ejaculate down into the everted female [[Exotics_-_Anatomy_of_the_Female_Reproductive_System_-_Anatomy_%26_Physiology#Oviduct|oviduct]].
  
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=== Protrusible Phallus ===
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== Protrusible Phallus ==
  
 
* Ratites and Anseriformes
 
* Ratites and Anseriformes
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* Elongated, capable of true intromission into the female [[Avian_Vent_and_Cloaca_- Anatomy & Physiology#The_Cloaca|cloaca]].
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* Elongated, capable of true intromission into the female cloaca.
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* Distal end lies enclosed in a cavity on the floor of the [[Avian_Vent_and_Cloaca_- Anatomy & Physiology#The_Cloaca|cloaca]] and becomes engorged with lymphatic fluid.
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* Distal end lies enclosed in a cavity on the floor of the cloaca and becomes engorged with lymphatic fluid.
 
** Anseriformes have a curved, fibrous phallus that conveys semen via a spiral groove.
 
** Anseriformes have a curved, fibrous phallus that conveys semen via a spiral groove.
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== Accessory Sex Organs ==
 
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The male avian has no [[Accessory Sex Glands - Anatomy & Physiology|accessory sex glands]] that are seen in mammals. Instead, they have accessory reproductive organs:
 
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* Paracloacal Vascular Bodies
 
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* Dorsal Procotodeal Gland
 
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* Lymphatic Folds
 
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These are either in proximity to, or are an integral part of the [[Avian_Vent_and_Cloaca_- Anatomy & Physiology#The_Cloaca|cloaca]].
 
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=== Paracloacal Vascular Bodies ===
 
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* Found alongside the receptacle of the vas deferens.
 
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* Contribute to the lymphatic erection of the either cloacal or phallic tissue.
 
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* Release a lymph-like transparent transudate when engorged.
 
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=== Dorsal Procotodeal Gland ===
 
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* Found on the dorsal [[Avian_Vent_and_Cloaca_- Anatomy & Physiology#The_Cloaca|proctodeum]].
 
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* Develop to varying degrees.
 
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* Undergo [[Cell Growth Disorders#Hypertrophy|hypertrophy]] in response to '''steroid sex hormones'''.
 
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=== Lymphatic Folds ===
 
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* Found within the wall of the [[Avian_Vent_and_Cloaca_- Anatomy & Physiology#The_Cloaca|procotodeum]].
 
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* Contribute to the lymphatic erection of the either cloacal or phallic tissue.
 
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* Release a lymph-like transparent transudate when engorged.
 
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[[Category:Avian Reproduction]]
 
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[[Category:Bullet Points]]
 

Revision as of 13:24, 21 July 2008

BACK TO REPRODUCTIVE SYSTEM
BACK TO EXOTICS
BACK TO AVIAN REPRODUCTIVE ANATOMY & PHYSIOLOGY
BACK TO MALE AVIAN REPRODUCTIVE ANATOMY & PHYSIOLOGY



Testes

  • Bean-shaped, paired
  • Lie near the cranial pole of the kidney
  • Medially, they lie close to the aorta and caudal vena cava.
  • Each testical suspended by a short mesochorium and surrounded medially by the abdominal air sac.
  • Left tends to be larger than right in immature birds.
  • Dimentions increase rapidly with sexual activity.
  • In the non-breeding season, testes shrink to almost nothing and become hard to visualize.
  • Dormant testes light brown/yellow in colour, turn white when sexually active.
    • In some psittacine species, immature or dormant testes may appear black due to melanocytes located in the interstitium.
  • Semniferous tubules produce sperm from the epithelium.
  • Interstitial Leydig cells lie between semniferous tubules.
  • Tunical Albiguinea thinner than in mammals.
  • No Pampiniform plexus.
  • Epididymis is small and can be considered absent. Sperm maturation occurs in the Vas Deferens.
  • Vas Deferens closely associated with the Ureter in the dorsomedial midline coelom, distinguished by its zig-zag appearance.
  • Vas Deferens enters dorsal wall of the Urodeum.
  • No accessory sex glands.

Phallus

  • Most birds lack a true phallus.
  • When present, the avian phallus is soley reproductive and becomes engorged by lymph fluid instead of blood during erection.
  • Owing to the lack of accessory sex glands, avian semen has low volume.
    • Some lymph may contribute to the seminal fluid.
  • Sperm remains viable in the female tract for much longer than in mammals.
    • May survive for 5-6 days.


Absence of Phallus

  • Psittacines, Passerines, Pidgeons and birds of prey all have no phallus.
  • Copulate by transferring semen from the everted Cloaca directly into the female oviduct.

Non-Protrusible Phallus

  • Rudimentary non-protrusible phallus is seen in male Turkeys and Chickens.
  • Lies on the ventral lip of the vent.
  • Consists of a small medial tubercle intimately associated on each side with lymphatic folds and vessels.
  • When erect with lymph, the phallus develops a median groove.
    • Median groove permits passage of ejaculate down into the everted female oviduct.

Protrusible Phallus

  • Ratites and Anseriformes
  • Elongated, capable of true intromission into the female cloaca.
  • Distal end lies enclosed in a cavity on the floor of the cloaca and becomes engorged with lymphatic fluid.
    • Anseriformes have a curved, fibrous phallus that conveys semen via a spiral groove.
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