Oestrus Flashcards

1
Q

Oestrus cycle

A

repetitive patterns of hormones and behaviour which lead to the ovulation of a follicle (oocyte release).

Can be describe in terms of hormones, state of the ovaries and behaviour.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How long is the oestrus cycle in the cow?

A

21 days

(18-24 days)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the phases of the oestrus cycle (classified behaviourally)?

A
  • Prooestrous
  • Oestrus
  • Metoestrus
  • Dioestrus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the phases of the oestrus cycle (classified by ovarian activity)?

A
  • Follicular phase - oestradiol dominates
    • Comprises pro-oestrus and oestrus phase
  • Luteal phase - progesterone dominates
    • Comprises metoestrus and dioestrus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How does the luteal phase end?

A
  • Absence of foetus –> leads to luteolysis
  • Progesterone falls as a consequence of luteolysis
  • Progesterone falling enables oestradiol and therefore LH to rise.
  • Positive feedback eventually results in LH surge which triggers ovulation during oestrus (follicular phase)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Dominant follicle

A

Fluid filled structure containing a single egg

Dominant over other follicles on the ovary

Forms corpus luteum once ovulated

There can be multiple dominant follicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Metoestrus

A

Succeeds oestrus and sees the formation of the corpus luteum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the hormonal and behavioural indications of oestrus

A
  • High E2
  • Female is receptive to the male
    • Signs differ between species, include:
    • Lordosis
    • Lifting tail
    • Swollen vulva
    • Restlessness/seeking male
    • Standing to be mounted
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the hormonal and behavioural indicators of dioestrus

A
  • High levels of P4
  • Female rejects the male
    • May be openly aggressive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

When is d0 or d1?

A

1st day of cycle

= 1st day of oestrus

This is different to the menstrual cycle (where ovulation is mid-cycle as opposed to near the start)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the hormonal, physiological and behavioural changes in the follicular phase

A

Follicular phase = pro-oestrus + oestrus

  • The ovarian follicles mature, secreting increasing concs. of E2 into the blood
  • LH rises to surge at ovulation
  • FSH rises then falls at the end of oestrus
  • Oestrus behaviour is observed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the hormonal, physiological and behavioural changes in the luteal phase

A

Luteal phase = metoestrus + dioestrus

  • Ovarian follicle(s) ovuluate to produce 1+ corpus luteum
  • CL secretes progesterone into the blood
  • This phase ends with luteolysis caused by PGF2a
  • Follicles continue to develop in waves but fail to ovulate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly