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− | <big><center>[[Reproductive System|'''BACK TO REPRODUCTIVE SYSTEM''']]</center></big>
| + | == Introduction == |
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− | <big><center>[[Reproductive_System#Exotics|'''BACK TO EXOTICS''']]</center></big>
| + | 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>[[Exotics_-_Avian_Reproductive_Anatomy_and_Physiology_-_Anatomy_%26_Physiology|'''BACK TO AVIAN REPRODUCTIVE ANATOMY & PHYSIOLOGY''']]</center></big>
| + | == Testes == |
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− | <big><center>[[Exotics_-_Reproduction_in_the_Male_Avian_-_Anatomy_%26_Physiology|'''BACK TO MALE AVIAN REPRODUCTIVE ANATOMY & PHYSIOLOGY''']]</center></big>
| + | [[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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− | = Testes =
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| * Bean-shaped, paired | | * Bean-shaped, paired |
| * Lie near the cranial pole of the kidney | | * Lie near the cranial pole of the kidney |
| * 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. |
− | * Dimentions increase rapidly with sexual activity. | + | * Dimensions 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. |
− | * '''Semniferous tubules''' produce '''sperm''' from the epithelium.
| + | * Tunical Albiguinea thinner than in mammals. |
− | * Interstitial '''Leydig cells''' lie between semniferous tubules.
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− | * Tunical Albiguinea thinner thsn in mammals. | |
| * '''No Pampiniform plexus'''. | | * '''No Pampiniform plexus'''. |
− | * '''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'''. |
| + | * '''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. |
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| + | == Phallus == |
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| + | * 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. | | * 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 == | + | === Absence of Phallus === |
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| * Psittacines, Passerines, Pidgeons and birds of prey all have no phallus. | | * Psittacines, Passerines, Pidgeons and birds of prey all have no phallus. |
− | * 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]]. | + | * 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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| + | === Non-Protrusible Phallus === |
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| + | * 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]]. |
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| + | === Protrusible Phallus === |
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| + | * 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. |
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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: |
| + | * 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]]. |
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| + | === Paracloacal Vascular Bodies === |
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| + | * 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. |
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| + | === Dorsal Procotodeal Gland === |
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| + | * 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'''. |
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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]]. |
| + | * Contribute to the lymphatic erection of the either cloacal or phallic tissue. |
| + | * Release a lymph-like transparent transudate when engorged. |
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− | == Non-Protrusible Phallus ==
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− | == Protrusible Phallus ==
| + | [[Category:Avian Reproduction]] |
| + | [[Category:Bullet Points]] |