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Reptile Reproduction - Anatomy & Physiology (view source)
Revision as of 14:01, 23 July 2008
, 14:01, 23 July 2008no edit summary
** Argenine vasotocin has the same function as Oxytocin in mammals.
** Argenine vasotocin has the same function as Oxytocin in mammals.
== Temperature Dependent Sex Determination (TDSD) ==
== Sex Determination ==
Two types of sexual determination can occur in reptiles, Gynotypic or Temperature Dependent Sex Determination (TDSD).
=== Gynotype Sex Determination ===
* Reptiles differ from mammals in that the female is heterogametic (ZW) and the male is homogemetic (ZZ).
=== Temperature Dependent Sex Determination (TDSD) ===
* Occurs in many lizards, some turtles and all crocodiles.
* Sex of the embryo is not determines by sex chromosomes.
* Sex of the embryo is determines by the incubation temperature during the early and middle incubation period.
** The time when the embryonic gonad develops into either testes or ovaries.
* Different temperatures act on the aromatase enzyme complex that converts testosterone to oestradiol.
** Oestrogen then binds the its receptor on the gonads to create females.
** To create males, enzymes convert testosterone to dihydrotestosterone, which binds to androgen receptors on the gonads.
==== Crocodiles ====
* Pivotal temperatures are important.
* Produce females at both high and low temperatures and males at intermediate temperatures.
* E.G in alligators:
** Incubation at 30
==== Chelonia ====
==== Lizards ====
== [[Reptile Reproductive Anatomy and Physiology- Chelonia - Anatomy & Physiology|Tortoises, Turtles & Terrapins (Chelonia)]] ==
== [[Reptile Reproductive Anatomy and Physiology- Chelonia - Anatomy & Physiology|Tortoises, Turtles & Terrapins (Chelonia)]] ==