2. cyclicity across the species Flashcards
what are the functions of FSH
- follicular recruitment and growth
- oestrogen production
what are the functions of LH
- follicular dominance
- ovulation
- production of oestrogen and progesterone
the luteal phase is characterised/terminated by
- characterised by increaseing progesterone which remains elevated for >10 days
- luteal phase is terminated by luteolysis enabling a new follicular phase which culminates in ovulation
discuss the oestrus cycle in the bitch
- have an extended luteal phase
- regarless of if pregnant
- progesterone peaks then slowly declines followed by period of anoestrus
compare the hormone levels in a pregnant vs non-pregnant bitch
- progesterone only slightly greater in pregnant dog from day 21
- therefore cannot tell difference between pregnant and non-pregnant before 21 days by progesterone test
- rapid fall in progesterone occurs at partuition
- progesterone still decreases as pregnancy continues, so prolactin increases to help maintain CL
how is termination of the luteal phase achieved in the bitch
- repeated administration of a prolactin inhibitor but only when prolactin is principal luteotrophic hormone (if progesterone dominant, doesnt work)
- termination of luteal phase leads to anoestrus in dog (not follicular phase)
what is the role of prolactin in the bitch
- the early CL is autonomous
- from day 21 progesterone concentrations start to decline
- prolactin is the principal luteotrophic hormone
- declining progesterone stimulates prolactin secretion which in turn results in support of the CL and maintenance of progesterone
- despite this progesterone concentration continue to decline
- progesterone only produced by the CL in the ovary in the bitch and queen so ovariectomy during pregnancy will result in pregnancy loss
every non-pregnant bitch has which hormone and clinical signs in the luteal phase and why
- elevated progesterone => mammary enlargement and potential for milk secretion
- elevated prolactin => milk production and behavioural changes typical of pregnancy
- this is because it helps to help raise puppies from other bitches in the pack
cats have which kind of breeding pattern
- seasonal long day breeders
- polyoestrus
- induced ovulators
cats reach puberty when
onset influenced by season
- sometimes time from birth to puberty varies and can be <6months. if born september will have to wait until long day
wild cats have repeated oestrus signs between which months
march to october
discuss ovulation in the queen
- require stimulation of mating to ovulate
- if no stimulation, no ovulation
- absence of ovulation = regression of follicles
describe cyclicity in the cat
- cats will have repeated oestrus with no luteal phase
- if not mated, follicle regresses and a new follicular wave develops
- average interval between oestrus is 16-21 days
mating in the queen in oestrus will cause which hormone to surge
LH –> leads to ovulation
