Reproduction of fish and reptiles Flashcards
Where do the testes lie?
The gonads lie near the cranial pole of the kidney in many species but in Snakes the gonads caudal to gall bladder
Does puberty depend on age or size?
Onset sexual maturity varies and depends on size not age
The diet plays an important role and you can push puberty with the diet
In squamates which testis lies cranially?
Right cranial to Left in many squamates
Do reptiles have accessory sex glands?
No
Which reptiles have a penis and which have hemipenes?
Penis: Chelonians
Hemi-penes: Lizards, snakes
Where do the hemipenes lie?
Hemipenes are paired and kept in the tail base by the retractor penis muscle. During copulation the hemipenes is everted and becomes erect (vascular erection).
They may also have sharp keratinised spines or flounces
What is the sexual segment?
The sexual segment in the Distal convoluted tubules of the kidney which are only present in the breeding season. The cells that are there go from cuboidal to columnar and increase in size 2-4x. Large eosinophillic granules secreted into lumen
What is the function of the sexual segment?
Separate urine/semen copulation
Copulatory plug
Do females have two ovaries?
Some missing left oviduct
Do reptile have a uterus?
No
Where do the oviducts empty?
Oviducts empty into cloaca on the genital papillae
What do the oviducts consist of?
The oviducts consist of the: infundibulum, uterine tube, isthmus, uterus/shell gland and vagina but not all parts are present in all species.
Can reptiles be hermaphrodites?
Reptiles can also present hermaphroditism (intersex) where the females have a hemipene with or without ovitestes, for example the pit viper where intersexes are more common than true females and all pregnant animals are intersexes.
What is Parthenogenesis?
Is a type of asexual reproduction in which the offspring develops from unfertilized eggs
Occurs in around 30 spp of lizards
Where does fertilisation occur?
Occurs in the cranial oviduct and like birds the sperm is viable at body temperature so can be stored for up to 6 years
Females can store sperm from multiple males and multiple matings
What does oviparous mean?
Oviparous – egg-laying (all chelonians, most squamates)
Define viviparous, what are the two subtypes?
Viviparous – live-bearing (20% squamates)
1. Lecithotrophy
Egg in tract until hatching (nutrients mostly from yolk)
Hatch at time of parturition
2. Matrotrophy
Livebearing
Chorioallantoic placenta (nutrients from mother)
What are the pros and cons of viviparous young bearing in reptiles?
With viviparous bearing the foetus takes up space in the mother which limits GI function so little feeding can take place in the latter stages and only really allows one clutch per year. However in colder climates it will keep embros warm during incubation.
How long do eggs gestate before hatching?
1-2 months
What gonadotrophins do chelonians have?
FSH & LH in chelonians – similar role to mammals
FSH: ovarian growth, follicular development
LH surge: ovulation – many chelonians
What gonadotrophins do squamates have?
1 gonadotropin - FSH-like compound
No LH equivalent
What is the purpose of oestrogen and progesterone?
Oestrogen is involved in yolk development like it is in birds and in seasonal breeders it is high in the early season for vitellogenesis.
Progesterone in chelonians surges before ovulation like birds. Progesterone Inhibits oviduct contraction, prevents expulsion embryo. In seasonal breeders: high after ovulation, during gestation in viviparous spp.
What is the stimulus in seasonal breeders?
The stimulus is temperature change:
Temperate spp: Spring after cooling period (hibernation/brumation)
Tropical boidae: Cooler period breeding (don’t hibernate), or year round
If rainfall seasonal, rainfall is trigger
Birds need priming before mating, do reptiles need this?
Female primed for Egg production by exposure to sexually mature male before mating
If no priming will make shell-less or very thin shelled eggs
Males exposed to females stimulates gonadal development
