Oestrus Cycle In Small Animals

Question 1

What is the cycle length of rodents/rats

Answer 1

4-5 days, each stage 1 day on average

Question 2

What are the 4 stages of laboratory rodent oestrus cycle

Answer 2

Pro-oestrus
Oestrus
Met-oestrus
Di-oestrus

Question 3

What happens in the 4 main stages of oestrus cycle

Answer 3

1. Pro-oestrus—> During proestrus the CL regresses (progesterone declines) and a preovulatory follicle undergoes its final growth phase (estradiol increases)
2. Oestrus—> Ovulation usually occurs (cows ovulate during met-oestrus)
   (Proestrus and oestrus comprise the follicular phase)
3. Met-oestrus—> Corporus luteum develop and function at optimum during diestrus
4. 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

Question 4

What stage of oestrus cycle produces the Oestradiol increased levels in rodents

Answer 4

Pro-oestrus

Question 5

What stage does the LH surge occur at?

Answer 5

Afternoon of pro-oestrus day

Question 6

At what stage do rodents become receptive to males in oestrus cycle?

Answer 6

Oestrus phase

Question 7

In what occasion will progesterone production be low?

Answer 7

When there’s no mating

Question 8

What is progesterone (P4) essential for in oestrus cycle
What is prolactin essential for

Answer 8

essential for the surge (neuro P4) and for ovulation, and prolactin is essential for luteal function

Question 9

Diagram of rodents oestrus cycle

Answer 9

On anki

Question 10

What stage does receptivity occur in rodent oestrus cycle

Answer 10

End of pro-oestrus to oestrus- due to progesterone rise

Question 11

Prolactin in rodent is luteotrophic. What does this mean?

Answer 11

Supports corpus luteum formation

Question 12

Pseudopregnancy
-in what animal
-what is it
-what does this mean to animal

Answer 12

-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

Question 13

Name the 4 stages of the bitch cycle and how long each stage is

Answer 13

1. Pro-oestrus—> 7-9 days
2. Oestrus—> 7-9 days
3. Metoestrus—> 2+ months
4. Anoestrus—> 2-5 months (variable)

Question 14

How long is the average oestrus cycle?

Answer 14

7 months

Question 15

In general is the bitch seasonal or not seasonal oestrus cycle?

Answer 15

Not seasonal

Question 16

Most data on repro cycles come from what bitch?

Answer 16

Beagle

Question 17

What does bitch anoestrus phase lead to

Answer 17

Variability in breeds as its length time is very variable

Question 18

Describe the hormonal changes occurring in a non pregnant bitch cycle

Answer 18

On anki

Question 19

What is Diapedesis bleeding in a bitch and when does it occur?

Answer 19

Slight Bleeding around vulva cause by effect of Oestradiol on repro tract during poreostrus

Question 20

How can we determine stage of oestrus cycle of bitch?

Answer 20

Using a vaginal smear

Question 21

hat brings the bitch into heat/oestrus

Answer 21

Lutenization and onset of progesterone production

Question 22

Ovulation occurs how long after surge?

Answer 22

2 days

Question 23

In al species it is the __________ occyte that is ovulated. What is the exception in the dog?

Answer 23

Secondary
-it is the primary oocyte that is fertilised

Question 24

Epithelium of vagina is…

Answer 24

Stratified

Question 25

What does Oestradiol lead to?

Answer 25

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)

Question 26

At what stage is the bitch in her ‘receptive to male’ stage

Answer 26

Oestrus stage

Question 27

Which cells are found in which stage of bitch oestrus cycle?

Answer 27

On anki

Question 28

Compare the bitch and cow oestrus cycle

Answer 28

On anki (2 cards)

Question 29

Which species is an induced ovulator

Answer 29

Cat

Question 30

What does induced ovulator mean?

Answer 30

The GnRH surge is caused by mating (neuroendocrine reflex) instead of decline in Oestradiol and ^ in progesterone which leads to GnRH surge

Question 31

What happens to the heat/oestrous periods in the cat oestrus cycle to induce a GnRH surge

Answer 31

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

Question 32

In cat oestrous cycle progesterone rises when…

Answer 32

Corpora lutea develop

Question 33

Describe what happens in cat oestrous cycle

Answer 33

On anki

Question 34

What are the 2 outcomes of inducing ovulation in cat via mating?

Answer 34

1. Pseudopregnancy—> if no conception: CL regression at 5-6 weeks and the queen comes on heat again 2. Pregnancy—> placenta maintains high progesterone to term after CL regression