Oestrus Cycle In Small Animals Flashcards
What is the cycle length of rodents/rats
4-5 days, each stage 1 day on average
What are the 4 stages of laboratory rodent oestrus cycle
Pro-oestrus
Oestrus
Met-oestrus
Di-oestrus
What happens in the 4 main stages of oestrus cycle
- Pro-oestrus—> During proestrus the CL regresses (progesterone declines) and a preovulatory follicle undergoes its final growth phase (estradiol increases)
- Oestrus—> Ovulation usually occurs (cows ovulate during met-oestrus)
(Proestrus and oestrus comprise the follicular phase) - Met-oestrus—> Corporus luteum develop and function at optimum during diestrus
- Di-oestrus—> ovaries show increased numbers of large follicles with a single, follicular fluid-filled antral cavity. Maximal progesterone produced
The last 2 are the luteal phase
What stage of oestrus cycle produces the Oestradiol increased levels in rodents
Pro-oestrus
What stage does the LH surge occur at?
Afternoon of pro-oestrus day
At what stage do rodents become receptive to males in oestrus cycle?
Oestrus phase
In what occasion will progesterone production be low?
When there’s no mating
What is progesterone (P4) essential for in oestrus cycle
What is prolactin essential for
essential for the surge (neuro P4) and for ovulation, and prolactin is essential for luteal function
Diagram of rodents oestrus cycle
On anki
What stage does receptivity occur in rodent oestrus cycle
End of pro-oestrus to oestrus- due to progesterone rise
Prolactin in rodent is luteotrophic. What does this mean?
Supports corpus luteum formation
Pseudopregnancy
-in what animal
-what is it
-what does this mean to animal
-in rodents
-state due to prolonged function of CL (corpal lutea) lifespan due to a luteotrophic action of Prolactin pulses which occur following vaginal stimulation. Animal thinks its pregnant but actually is not
Name the 4 stages of the bitch cycle and how long each stage is
- Pro-oestrus—> 7-9 days
- Oestrus—> 7-9 days
- Metoestrus—> 2+ months
- Anoestrus—> 2-5 months (variable)
How long is the average oestrus cycle?
7 months
In general is the bitch seasonal or not seasonal oestrus cycle?
Not seasonal
Most data on repro cycles come from what bitch?
Beagle
What does bitch anoestrus phase lead to
Variability in breeds as its length time is very variable
Describe the hormonal changes occurring in a non pregnant bitch cycle
On anki
What is Diapedesis bleeding in a bitch and when does it occur?
Slight Bleeding around vulva cause by effect of Oestradiol on repro tract during poreostrus
How can we determine stage of oestrus cycle of bitch?
Using a vaginal smear
hat brings the bitch into heat/oestrus
Lutenization and onset of progesterone production
Ovulation occurs how long after surge?
2 days
In al species it is the __________ occyte that is ovulated. What is the exception in the dog?
Secondary
-it is the primary oocyte that is fertilised
Epithelium of vagina is…
Stratified
What does Oestradiol lead to?
Proliferation in repro tract & vascularisation and oedema
an increase in luteinising hormone (LH) levels, which in turn results in an egg becoming mature (able to be fertilised by sperm) and released from the ovary (ovulation)
At what stage is the bitch in her ‘receptive to male’ stage
Oestrus stage
Which cells are found in which stage of bitch oestrus cycle?
On anki
Compare the bitch and cow oestrus cycle
On anki (2 cards)
Which species is an induced ovulator
Cat
What does induced ovulator mean?
The GnRH surge is caused by mating (neuroendocrine reflex) instead of decline in Oestradiol and ^ in progesterone which leads to GnRH surge
What happens to the heat/oestrous periods in the cat oestrus cycle to induce a GnRH surge
They alternate with interoestrus periods during breeding season. Oestradiol rises occur regularly during the breeding season
Constant heat, non heat, heat, non heat on repeat until they encounter a male and ovulate
In cat oestrous cycle progesterone rises when…
Corpora lutea develop
Describe what happens in cat oestrous cycle
On anki
What are the 2 outcomes of inducing ovulation in cat via mating?
- Pseudopregnancy—> if no
conception:
CL regression at 5-6 weeks and the queen comes on heat again - Pregnancy—> placenta maintains high progesterone to term after CL regression
