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

Revision as of 13:54, 4 July 2008

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 thsn 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.

@@ Line 1: / Line 1: @@
-== Introduction ==
-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.
 == Testes ==
-[[Image:Chicken male dissection.jpg|thumb|right|150px|Dissection of the Male Avian Reproductive Tract- Courtesy of Andrew Crook, Copyright RVC 2008]]
 * 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.
-* Dimensions increase rapidly with sexual activity.
+* 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.
-* Tunical Albiguinea thinner than in mammals.
+* '''Semniferous tubules''' produce '''sperm''' from the epithelium.
+* Interstitial '''Leydig cells''' lie between semniferous tubules.
+* Tunical Albiguinea thinner thsn 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'''.
-* Convoluted '''semniferous tubules''' comprised of '''spermatogonia''' (germ cells) and '''Sertoli cells''' make up the bulk of the testes.  These are responsible for '''spermatogenesis'''.
+----
-* '''Interstitial Leydig cells''' produce male androgens.
-* Mature spermatozoa exit into the '''rete testes''', which connects to the cranial '''epididymis'''.
-** Rete testes not present in all birds.
-** Epididymis considered vestigial in birds.
-*** Sperm maturation occurs in the '''ductus deferens'''.
-* Epididymis lies along the dorsomedial aspect of the testes.
-* Spermatazoa exit the epididymis and enter the ductus deferens.
-** Ductus deferens is closely associated with the Ureter in the dorsomedial midline coelom, distinguished by its zig-zag appearance.
-** Under hormonal control, more convoluted in the breeding season.
-* Ductus deferens enters the dorsal wall of the '''cloacal urodeum'''.
-** Straightens and abruptly widens at ats junction with the cloaca.
-*** Structure known as the '''receptacle''' in Passerines and Budgerigars.
-*** Receptacle appears bean-shaped when engorged with semen.
-*** Birds that do not have the receptacle structure have little sperm storage capacity.
 == Phallus ==
-* Most birds lack a true phallus.
-* Analogue of the mammalian penis.
-* 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.
-* 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 [[Avian_Vent_and_Cloaca_- Anatomy & Physiology#The_Cloaca|Cloaca]] directly into the female [[Avian Female Reproductive System#Oviduct|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 [[Avian Female Reproductive System#Oviduct|oviduct]].
-=== Protrusible Phallus ===
-* Ratites and Anseriformes
-* Elongated, capable of true intromission into the female [[Avian_Vent_and_Cloaca_- Anatomy & Physiology#The_Cloaca|cloaca]].
-* 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.
-** Anseriformes have a curved, fibrous phallus that conveys semen via a spiral groove.
-== Accessory Sex Organs ==
-The male avian has no [[Accessory Sex Glands - Anatomy & Physiology|accessory sex glands]] that are seen in mammals. Instead, they have accessory reproductive organs:
-* Paracloacal Vascular Bodies
-* Dorsal Procotodeal Gland
-* Lymphatic Folds
-These are either in proximity to, or are an integral part of the [[Avian_Vent_and_Cloaca_- Anatomy & Physiology#The_Cloaca|cloaca]].
-=== Paracloacal Vascular Bodies ===
-* Found alongside the receptacle of the vas deferens.
-* Contribute to the lymphatic erection of the either cloacal or phallic tissue.
-* Release a lymph-like transparent transudate when engorged.
-=== Dorsal Procotodeal Gland ===
-* Found on the dorsal [[Avian_Vent_and_Cloaca_- Anatomy & Physiology#The_Cloaca|proctodeum]].
-* Develop to varying degrees.
-* Undergo [[Cell Growth Disorders#Hypertrophy|hypertrophy]] in response to '''steroid sex hormones'''.
-=== Lymphatic Folds ===
-* Found within the wall of the [[Avian_Vent_and_Cloaca_- Anatomy & Physiology#The_Cloaca|procotodeum]].
-* Contribute to the lymphatic erection of the either cloacal or phallic tissue.
-* Release a lymph-like transparent transudate when engorged.
-[[Category:Avian Reproduction]]
-[[Category:Bullet Points]]

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

Revision as of 13:54, 4 July 2008

Testes

Phallus

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