Week 1 Flashcards
describe the anatomy and function of the hypothalamus?
situated below the thalamus but above the pituitary. with the medulla oblongata caudal function - integrator of neurone + endocrine system - regulates reproduction - the important areas; pre-optic area, media-basal hypothalamus.
what is GnRH?
is a releasing hormone responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary.
Prolactin is inhibited when released, regulating negativity.
what is the release pattern of GnRH?
pulsatile -
GnRH binds to receptor on gonadrotope cell in AP, but must be pulsatile to have an intraceuller effect.
how is LH and FSH secretion regulated?
LH release and synthesis under GnRh regulation
FSH synthesis and release constitutive + under control by peptide regulators: Oestradiol!!
describe the hormone feedback from a release of GnRH?
⬆️GnRH = ⬆️LH + ⬇️FSH = oestradiol ovarian peptides ➡️ progesterone androgens causing GnRH surge and less FSH.
describe the general histological arrangement of the ovary?
surface epithelium layer, tunica albuginea, medulla, cortex.
ovary derived from oocyte - arrested in diplotene stage of meiosis, completed a fertilisation.
what are primordial follicles?
folliculogenesis, primordiale pool - mid late gestations
affected by age, breed, nutrition stage.
name the 5 follicles in the ovary?
primary secondary tertiary preovulatory atretic
describe primary follicle?
start, becomes cuboidal surrondnded by interstitial fluid, onset of follicular growth.
describe secondary follicles?
cell proliferation, often termed ‘prenatal’
describe tertiary follicles?
vesicular or ontral
antrum formation as granulosa and theca proliferation .
Gonodropoptin - dependent growth, driven by FSH, strike genesis increasing markers.
describe preovulatory follicles?
very enlarged, protruding on ovarian surface, except at hilus, hormones trigger ovulation
describe atretic follicles?
fast of majority > 99% sudden death of granuloma cells. Apoptotic process.
early Atresia - necrotic granulosa cells
late atresia - more necrotic granulosa cells.
describe the clinical application of follicle function?
manipulation of follicle function, oestrus synchronisation, super ovulation (MOET)
what does luteolysis involve?
PGF2a
Oxytocin.
what are neoplasms?
granulosa cell tumours
what is follicular devoplemnt?
‘ovarian reserve’ and recruitment of primordial follicles.
primordial follicle pools - resting follicles present form birth in females.
devolpment includes: recruitment, follicular grow and ovulation.
what percentage of growing follicles make it to ovulation?
1%
summarise the follicular growth in cows?
takes 3 months (150 days)
almost all follicles move into atresia death
LH ans FSH levels important in final stages of atrial follicle growth and development.
after recruitment - primary and secondary follicles respond to FSH + early ant rail follicles with response to LH.
Antral follicles produce steroid hormones = acerbate growth
what is the main function of progesterone?
synthesed by LH theca cells - converted into androgens
cholesterol uptake by theca cells turns into progestrone.
how is oestradiol produed?
androgens from LH theca cells pass through granulosa cells + converted into oestradiol
armature enzyme used for conversion
what is follicular wave growth?
non-ovulatory species (one offspring)
small astral follicles become complete FSH-dependent.
but the last follicle becomes LH dependent
what does the last follicle become dependent o and what does this cause?
dependent on LH pulse frequency and determines if dominant follicle growth occurs.
why must there be frequent Lh pulses occurring for dominant follicle growth?
frequent pulses = max amount of oestradiol produced for follicle growth + ovulate.
final masturation and ovulation.