female physiology

Question 1

Identify the major female reproductive hormones, the structures responsible for their synthesis and describe their endpoint actions

Answer 1

already know the others
Gonadal -
Estradiol (E2)
Progesterone (P4)

Question 2

Explain the HPG axis, including feedback mechanisms

Answer 2

GnRH- surge centre, tonics centre
PVN - oxytocin

FHS + LH = AP
Oxytocin = PP

Surge centre vs tonic (one does big surges and on does some small drops)

Surge = LH surge = pre-ovulatory LH surge (why not in male)

Follicles
LH binds to Theca interna cells (outside of basement membrane) —> cause these cells to produce testosterone

FSH binds to granulosa cell ( in the zone granulosa), drives T to estradiol

Estradiol action (key at mating)
brain, female tract (bull shit here)

Inhibit, E2 - blocks FSH (negative feedback)

Low E2 + high P4 limits GnRH secretion

Postive feedback loops - high E2 on surge centre = surge = ovulation = (follicle positive feedback on E2)

LH bind to luteal cells of the corpus luteum = P4 production

Question 3

Progesterone

Answer 3

Secreted from the CL
acts on mammary glands +, endometrium +, myometrium - ( decrease tone), brain -ve m behaviours.

P4 is about suppression of GnRH = blocks surge, reduce pause on tonic. Therefore there is no ovulation will occurring when a CL is present.

Question 4

PGF2a

Answer 4

Causes luteolysis -
Produced = utrine endometrium
Delivered vis uterine vein and ovarian artery counter current

Question 5

Other relevant hormones

Answer 5

Question 6

explain the four phases and how the hormones interact

Answer 6

Question 7

Question 8

Define the phases and stages of the estrous cycle

Answer 8

Oestrus cycle can be divided into
Follicular phase (E2 dominant), ends at ovulation, 20% total time.
Luteal phase (P4 dominant), CLs on ovary, ends at luteolysis (80% of cycle)

Stages of estrous cycle
Proestrus - follicular phase, follicle growth, increasing E2, decreasing P4.

Estrus - follicular phase, sexual receptivity, peak E2.

Metestrus - Luteal phase, CL formation, Increasing P4, decreasing E2

Diestrus - luteal phase, full fx CL, sustained high P4

Question 9

Describe how behaviour and hormones change across different phases/stages of the oestrus cycle characteristics

Question 10

Anestrus

Answer 10

Anestrus - low E2 and P4 - from insufficient GnRh release (no ovulatory follicles, no corpora lutea)
first ovulation after anestrus is often silent ( no P4 priming)

Question 11

Define monoestrous and polyestrous, including which species are monestrous and polyestrous

Answer 11

seasonality is driven by daylight and melatonin secretion

Question 12

Describe the concept of reproductive seasonality, including which species are short and long day breeders

Answer 12

Cows - polyestrous
Sheep - short day breeder (Dec-june in Aus)
Horse - long day breeder (sep- mar in Aus)
Pig - polyestrous

often this is due to gestation length. so the female can have the energy to lactate

Question 13

Canine estrus cycle difference

Answer 13

Question 14

Estrus cycle for the feline

Answer 14

Question 15

take home points of lecture 2

Answer 15

Question 16

Explain the process of folliculogenesis, describing the impact of. Hormone signalling on follicle recruitment, selection, dominance and atresia

Answer 16

before follicular phase can occur, luteolysis needs to occur so progesterone becomes low. So it no longer inhibits GnRH secretion and LH surge.

Question 17

Folliculogenesis

Answer 17

Initial recruitment phase
Primordial to early antral follicle
Autocrine/paracrine control as happens all life (before puberty)

Cyclic recruitment phase
Antral to ovulatory follicle
Occurs each cycle
Driven by FSH/LH
Takes 10 days.

Question 18

Folliculogenesis

Answer 18

Initial recruitment phase
Primordial to early antral follicle
Autocrine/paracrine control as happens all life (before puberty)

Cyclic recruitment phase
Antral to ovulatory follicle
Occurs each cycle
Driven by FSH/LH
Takes 10 days.

Question 19

list the four steps of folliculogenesis

Answer 19

Recuirtment
selection
dominance

the ones that do not progress are called Atresia

Question 20

Follicle recruitment

Answer 20

Cohort of astral follicles recruited
Small follicles
E2 secretion begins
This is FSH dominant here

Question 21

Selection

Answer 21

A small group of recruited follicles start to develop t medium size
LH receptors starting
FSH still plays a roll

Question 22

Dominance

Answer 22

Only a few of 1 becomes the dominant
E2 secretion highest - thus completely dependent on LH
Inhibit secretion begins to block other follicles.

LH is key to final maturation of follicles
Thus the driving force of a follicles success is its expression of LH receptors.

Question 23

Atresia

Answer 23

Along each of the phases where cells to not go the next phase they undergo Atresia - degeneration.

Question 24

Explain the concept of follicular waves

Answer 24

Question 25

Describe the process of ovulation, including the normal controls and induced ovulation

Answer 25

Leading up to ovulation
leutolysis = decrease progesterone
GnRH/LH pulses increase in frequency
Increase in E2 by Theca interna cells and granulosa cells (as more of these cells are being developed as the follicle maturates)
Once E2 reaches threshold it causes a GnRH/LH surge
That causes ovulation

LH surge = causes the following cascade

Prostaglandin E2 (ovary Sec)
tissue remodelling + increased blood flow

Prostaglandin F2a ( Ovary Sec) - note different to endometrium secretion
Smooth muscle contraction
Connective tissue breakdown

Progesterone - produced by theca cells
weakens follicle walls

These pressure are what causes ovulation

Induced ovulators = mechanical stimulation for LH surge

Question 26

Explain the process of oogenesis, including prenatal and post-pubertal stages

Answer 26

Cumulus-oocyte complex (con) is what is secreted out.

Prenatal-
Go to primordial follicles prior to birth and stops till puberty

Post-LH surge
primary oocyte becomes M2 oocyte by spitting out a polar body of unwanted DNA

Fertilisation- second meiotic division
makes a second polar body before fertilisation, so is a haploid cells right before ovulation.

BIG difference = Canines only resume meiosis after ovulation. ( so both 1 and 2 metic divisions are in estrus, thats why fertilisation needs to occur after a few days

Question 27

follicualar phase take home points

Answer 27

Question 28

Major events of in the luteal phase

Answer 28

Luteinisation (CL formation)
Progesterone secretion (CL fx)
Luteolysis (CL destruction)

Question 29

Describe the formation fo the corpus luteum and explain its purpose

Answer 29

Progesterone secretion efficiency = number of cells and amount of vascularisation

Question 30

Explain the local and systemic actions of progesterone produced by CL

Answer 30

Progesterone production from cholesterol and LH at basal levels as signalling tonic centre.