Difference between revisions of "Avian Male Reproductive Tract - Anatomy & Physiology"
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= Phallus = | = 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. | * 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. |
Revision as of 13:15, 21 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.
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.