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ANIMAL PRODUCTION - Reproduction > 7 – Female Reproduction II > Flashcards

7 – Female Reproduction II Flashcards

1
Q

Follicular dynamics: continuous

A
  • Follicular growth and regression is a continuous process
  • Independent of the phase of the reproductive cycle
  • Not synchronized
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2
Q

Follicular dynamics: wave pattern

A
  • Reservoir of antral follicles in a resting stage
  • At a particular time (species dependent) one will grow and reach maturity during estrus
  • *greater than 95% of bovine estrous cycles are composed of either 2 or 3 follicular waves
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3
Q

Estrus cycle

A
  • Duration between 2 estrus (heats)
  • Bovine=23 days
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4
Q

Dynamics of follicles consist of:

A
  1. Recruitment
  2. Selection
  3. Dominance
    a. Polytocous species=multiple dominant follicles)
  4. Atresia
    *synchronized by interaction of 4 hormones
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5
Q

4 hormones that are synchronized

A
  • FSH
  • LH
  • Estradiol
  • P4 (progesterone)
  • *2 negative, 1 positive feedbacks
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6
Q

What controls GnRH release?

A
  • Tonic and surge centers in hypothalamus
  • Release of FSH and LH
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7
Q

Release of GnRH from tonic center neurons

A
  • Occurs spontaneously in a rhythmic fashion
  • Always activated
  • Does not have HIGH concentration
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8
Q

Release of GnRH from surge centre

A
  • Controlled by HIGH ESTROGEN
    o From growing antral follicles in form of estradiol
  • HIGH production of GnRH=high production of LH (LH surge)
  • Accompanied by low progesterone (from CL)
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9
Q

Role of progesterone

A
  • Essential to turn on surge center to achieve ovulation
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10
Q

Recruitment of follicles

A
  • Phase of follicular development in which cohort of small antral follicles begin to GROW
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11
Q

What precedes a follicular wave?

A
  • Surge of plasma FSH from tonic centre
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12
Q

Selection of follicles

A
  • Selected and either become atretic or develop further
  • Some follicles start shifting their dependence from FSH to LH=acquire LH responsiveness
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13
Q

Low estradiol concentrations

A
  • Negative feedback on hypothalamus so follicular wave can finish
    o Don’t need more FSH and LH
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14
Q

Dominant follicle

A
  • One that reaches the largest diameter
  • Produces increasing amounts of estradiol=positive feedback to A. pituitary
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15
Q

How does the dominant follicle become dominant?

A
  • FSH starts follicular wave
  • Post surge decline of FSH, growth of most follicles of a wave stop and begin to regress
  • *Maintains growth by transitioning dependence from FSH to LH
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16
Q

What happens once estradiol (from dominant follicle) reaches threshold level?

A
  • Negative to positive feedback of GnRH=surge of LH=OVULATION
17
Q

Peak estradiol concentration in follicular fluid of ovulatory follicle compared to anovulatory dominant follicles

A
  • Twice as high
18
Q

What happens at ovulation?

A
  • Antral contents are evacuated
  • Wall of ovulatory follicle collapses =CL
  • CL produces progesterone
19
Q

What is plasma progesterone concentration highly correlated with?

A
  • CL weight and volume
  • *if increased=inhibits SURGE center
20
Q

What happens when there is high progesterone from CL?

A
  • Tonic centre release GnRH
  • FSH
  • Growing follicles produce estradiol
  • Estradiol effect on SURGE centre is blunted
  • No LH surge
  • No ovulation
21
Q

What happens when there is low progesterone from CL?

A
  • Tonic centre release GnRH
  • FSH
  • Growing follicles produce estradiol
  • Estradiol is above threshold and activates SURGE centre
  • LH surge
  • Ovulation
22
Q
A
23
Q

Endogenous (or exogenous) progesterone in pregnant cows

A
  • Regular emergence of anovulatory follicular waves (tonic center is always activated)
  • Dose-related suppression of LH and dominant follicle growth
  • Max follicle diameter and intra-wave interval decreases
    *High progesterone (since pregnant)=inhibits surge center (eventually slightly decreases tonic centre)
  • Follicular wave through gestation EXCEPT LAST 21 days
24
Q

Luteolysis

A
  • when pregnancy does NOT occur
  • caused by prostaglandin F2-alpha
25
Q

Prostaglandin F2-alpha

A
  • released from endometrium around day 17-19 of cows estrous cycle
26
Q

Prostaglandin F2-alpha: mares

A
  • systemic route
27
Q

Prostaglandin F2-alpha: ruminants

A
  • local route
28
Q

Prostaglandin F2-alpha: pigs and camelids

A
  • both local and systemic
29
Q

Prostaglandin F2-alpha: dogs

A
  • similar profile in pregnant and non-pregnant
  • pseudopregnancy: drops slowly
  • pregnant: drops suddenly
30
Q

Prepubertal calves

A
  • Regular emergence of anovulatory follicular waves
31
Q

Regular emergence of anovulatory follicular waves in prepubertal calves

A
  1. FSH surges coupled to wave emergence
  2. Follicle dominance increases with age
  3. Max follicular diameter and intra-wave interval (IWI) increase with age
  4. Circulating LH concentration increases with age
32
Q

First ovulatory cycle is short

A
  • 8 days
  • Short-lived, under-developed CL
  • 1 follicular wave
33
Q

What starts the follicular wave?

A
  • FSH
34
Q

2-wave vs. 3-wave patterns: difference

A
  • Duration of cycle (19-20 or 22-23 days)
  • Interwave interval (10 or 8 days)
  • Max size of 2nd dom. Follicle (15 or 13 mm)
  • Onset of luteolysis (day 16 or 18)
    *pregnancy rate is the same
35
Q

Wave emergence size

A
  • 1mm
  • Dominant follicle emerges 6-12hrs earlier than first subordinate follicle
36
Q

Reproductive senescence

A
  • Gradual decline in reproductive capacity with age
  • Continued 2/3 wave patterns
  • Elevated FSH
  • Interovulatory and interwave interval do not change
  • CL smaller=lower progesterone
  • Fewer follicles at wave emergence
  • Lower super stimulatory response
  • Lower fertilization rate
37
Q

Mother vs. daughter pairs

A
  • Have same 2- or 3- wave pattern

ANIMAL PRODUCTION - Reproduction (17 decks)

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