Exam 2 (Estrous Cycle and Folliculogenesis)

Theca Interna

-Layer on the outside of the basement membrane that is directly touching it
-produces testosterone
-Simulated by LH

Recruitment Hormone Regulation

Follicles produce a small amount of E2 causing the Ant. Pit. to produce a large amount of FSH and the Post. Pit. to produce a small amount of LH.

Selection Hormone Regulation

Follicles produce more E2 and inhibin. Inhibin reduces the production of FSH. Post. Pit. produces more LH with increased E2.

Menstrual Cycle

-Primates
-No period of defined sexual receptivity
-A stage of endometrial sloughing
-The "start" of the menstrual cycle begins with menses, not ovulation

Estrous Cycle

-Adjective
-Farm animal species
-Predictable reproductive events that occur in a series and will continue until disrupted

Estrus

noun; refers to "heat" or the period of time when the female is receptive to the male

Anestrus

without estrus/cyclicity

Estrous cycle phases

-Follicular Phase
-Luteal Phase

Follicular Phase

-Growing and developing follicles
-Proestrus
-Estrus

Luteal Phase

-Corpus luteum is made
-Metestrus
-Diestrus

Polyestrous

-Estrous cycles that continue throughout the year, back-to-back
-Cow
-Sow

Seasonally Polyestrous

-Estrous cycles that cluster during a certain time/season of the year
-Ewe
-Doe
-Mare

Monoestrous

-Only one cycle per year
-Bitch

Estrous cycle of cow

-polyestrous
-21 days

Estrous cycle of mare

-Seasonally polyestrous
-21 days

Estrous cycle of sow

-polyestrous
-21 days

Estrous cycle of ewe

-Seasonally polyestrous
-17 days

Estrous cycle of queen

-Polyestrous
-17 days

Estrous cycle of bitch

-Monoestrous
-6 months

Female HPG Axis

-Tonic center
-Surge center (only in females)

Steroidogenesis

-Theca Interna
-Granulosa Cells

Granulosa Cells

-Inner most layer of cells
-Produces estradiol
-Simulated primarily by FSH
-Simulated by LH depending on follicle stage

StAR Protein

-Transport protein that tr4ansfers cholesterol into the inner mitochondrial membrane
-RATE LIMITING step

Folliculogenesis

ovarian follicles develop from primary into secondar and eventually into antral follicles that become eligible for ovulation

Primordial Follicles

-Microscopic
-Most immature
-Oocyte is surrounded by a single layer of squamous cells

Primary Follicle

-Microscopic
-Oocyte is surround by a single layer of cuboidal cells

Secondary Follicle

-Microscopic
-Oocyte is surrounded by 2+ layers of cells

Antral Follicles

-not microscopic
-Contains a developing fluid filled portion known as antrum

Follicular Waves

-Recruitment
-Selection
-Dominance

Recruitment

A cohort of follicles will be activated and start developing. Some follicles will continue to develop while others will undergo atresia

Selection

The follicles that reach develop (and not die) from recruitment will either continue to develop or undergo atresia

Dominance

Dominant follicle will acquire markers/receptors to continue to develop. Depending on the hormonal control, the follicle with either undergo atresia or ovulate.

Recruitment to Selection to Dominance

Granulosa cells must acquire LH receptors to allow the follicl4 to continue to develop! (selection)

FSH Dependent Folliculogenesis

-Recruitment
-Early Selection

LH Dependent Folliculogenesis

-Late Selection
-Dominance
-Dominance Preovulation

Dominance Hormonal Regulation

Follicle produces a large amount of E2 and inhibin. Causing a large reduction of FSH and a large increase in LH.

1st Follicular wave

-Occurs in either as P4 is rising or during peak P4 secretion.
-Follicles recruited and selected will undergo atresia.

2nd Follicular Wave

-Initiated before luteolysis
-Results in dominant follicles that will ovulate (Sometimes during a 3rd wave)

What causes Anestrous

-Pregnancy/ Postpartum
-Prepubertal
-Sickness
-Anorexia/ Obesity