Repro in reptiles and fish Flashcards
Describe the male reptile repro anatomy
Intra-abdominal testes
R testis cranial to L testis
No accessory sex glands
Label the male reptile repro anatomy
Describe the phallus in reptiles
Hemi-penes: lizards, snakes
Penis: chelonians
Keratinised spines
Describe the function of hemi-penes in reptiles
Only use one at a time during copulation (one is retracted) in case of damage
Retracted by retractor muscles after copulation
What is the function of the spur in snakes reproduction?
help to hold on to female during copulation
Describe the sexual segment in squamates
In the distal convoluted tubules of kidney
Cells change in breeding season:
- cuboidal-> columnar
- 2-4x increase in size
Large eosinophilic granules secreted into lumen
Kidneys look larger, paler and smoother during breeding season
What are the theorised functions of the sexual segment in squamates?
separate urine/semen at copulation
Copulatory plug
Describe reptile ovarian anatomy
ovaries paired
R larger than L (L undeveloped in some species)
Describe the anatomy of the oviduct in reptiles
Empties in cloaca: genital papillae
Secretes albumin -> shell
Includes:
- ostium
- aglandular segment
- magnum (albumin added)
- shell gland
- vagina
What are pre-vitellogenic follicles in reptiles?
Follicles that have been produced but haven’t had the yolk added to them
What are the stages of reproduction in reptiles?
Oocyte development - pre-vitellogenic follicle development
Vitellogenesis - yolk production
Oocyte maturation
Ovulation
Oviposition/parturition
What is parthogenesis in reptiles?
form of reproduction in which an egg can develop into an embryo without being fertilised by a sperm
30 species of lizard
Describe fertilisation in reptiles
Occurs in cranial oviduct
Sperm is viable at body temp
Sperm stored for months, years until environment is appropriate for fertilisation
What are oviparous reptiles?
egg-laying
all chelonians
most squamates
What are viviparous reptiles?
live-bearing
20% of squamates
What are the types of viviparity in reptiles?
Lecithotrophy:
- egg in tract until hatching
- hatch at time of parturition
Matrotrophy:
- livebearing
- chorioallantoic placenta
- RARE
How long is gestation in viviparous species of reptiles?
1.5-6 months
Hard to determine as fertilisation time unknown due to sperm storage
How long is the incubation period for oviparous reptile species?
incubation 1-2 months typically
Can be up to >270 days
What are the hormonal roles involved in chelonian reproduction?
FSH: ovarian growth, follicular development
LH surge: ovulation
Oestrogen
Progesterone
What are the hormones involved in squamate reproduction?
1 gonadotropin
FSH-like compound
No LH equivalent
Oestrogen
Progesterone
What are the roles of oestrogen in reptiles?
yolk development
seasonal breeders - high in early season
What is the role of progesterone in reptiles?
High during gestation (viviparous species)
High after ovulation
Ovulatory surge in chelonians (similar to birds)
What are the breeding stimuli in reptiles?
Temp change
Humidity
Day length (melatonin and pineal gland)
Presence of a mate (induced ovulators)
Environment
What is follicular stasis in reptiles, the causes and treatment?
Follicles produced but not ovulated
Accumulate -> inflammation -> infection -> rupture -> leakage
Causes:
- inappropriate diet/husbandry
- lack of brumation/hibernation
- lack of mating or presence of male
- stress
- illness
Treatment:
- not ill - correct husbandry
- ill - spay
Describe sex determination in snakes
Genetic
Female heterogamety
Male ZZ
Female ZW
Describe sex determination in lizards and chelonians
Genetic
Highly variably
Male heteromorphic (XX/XY)
Female heteromorphic (ZZ/ZW)
Homomorphic sex chromosomes
Describe temp dependent sex determination in reptiles
Incubation temp determines sex
Many chelonians, some lizards
Lizards:
- high temp = male
- low temp = female
Chelonians:
- high temp = female
- low temp = male
Some chelonians and lizards:
- extreme low or high temps = female
- intermediate temp = male
Describe lizard sexual dimorphism
Males often have ornamental anatomy e.g., horns, spikes
Describe chelonian sexual dimorphism
Females: flat plastron, short tail
Males: concave plastron, long tail
Describe the sexing methods of squamates
Manual eversion of hemipenes/popping - not recommended
Hydrostatic eversion of hemipenes - not recommended
Cloacal probing
Endocrinology - breeding season hormones
Ultrasonography - presence of eggs
Endoscopy
Describe male fish repro anatomy
Paired intra-abdominal testes
Sperm carried by ductus deferens to:
- bladder
- common urinary duct
- genital pore
Fish semen = milt
Describe female fish repro anatomy
Gymnovarian:
- oocytes into coelom -> oviduct remnants
Cystovarian:
- ovarian ducts (not oviducts)
What are the stages of reproduction in female fish?
Describe oviparous/egg laying fish species
most fish
external fertilisation
Describe vivparous/live bearing fish species
Fewer offspring than egg layers
Internal fertilisation
Lecithotrophy:
- nutrition from yolk sac
- fertilised eggs stay in body of parent
Matrotrophy:
- placenta-like structure
- very rare
Describe fish repro endocrinology
Pituitary gland releases GTH-I and GTH-II
GTH-I:
- FSH-like
- vitellogenesis
- gonadal development
- +ve feedback => GTH-II release
GTH-II:
- LH-like
- oocyte maturation
- ovulation
- progestins
Describe fish sex determination
Genetic dependent:
- male XY
- female ZW
Temp dependent
What environmental factors affect fish reproduction?
photoperiod
Temp
Presence of opposite sex
Currents/tides
Proximity to spawning area
What affects the onset of sexual maturity in reptiles?
diet
can ‘push’ onset of sexual maturity with diet
Describe the type of breeding in reptiles
Seasonal:
- temperate/subtropical - spring, after hibernation
- tropical - wet season
