Fish

Question 1

Describe the reproductive anatomy of a female

Answer 1

Gymnovarian (oviduct remnants) & cystovarian (ovarian ducts)

Question 2

What are the five stages of reproduction?

Answer 2

Oocyte development (gonadotrophin independent), vitellogenesis (yolk production – longest phase), oocyte maturation, spawning – release eggs & sperm, recovery – new oocyte development

Question 3

What is the difference between oviparous & ovoviviparous/viviparous?

Answer 3

Oviparous – lay eggs, 97% of fish, external fertilisation
Ovoviviparous – fertilised egg stays in body of parent, nutrition form yolk sac
Viviparous – placenta-like structure (very rare)

Question 4

What hormones are involved in the reproductive cycle?

Answer 4

GTH-I – vitellogenesis, early gonadal development

GTH-II – final oocyte maturation, ovulation

Question 5

How does GTH-I bring about vitellogenesis?

Answer 5

Binds to theca and granulose cells of follicles, testosterone is produced by the theca cells and converted into oestradiol by the granulosa cells, oestradiol acts on the liver and causes vitellogenin production

Question 6

What environmental factors affect reproduction?

Answer 6

Photoperiod, temperature, presence of opposite sex, currents, tides, stage of moon & spawning area

Question 7

What are the sex chromosomes of fish?

Answer 7

Male XY, female ZW

Question 8

What are the three reproductive modes of fish?

Answer 8

Separate male and female
Hermaphrodites – one animal switches (sequential) or is simultaneously both (synchronous)
Parthenogenesis – without fertilisation