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Endocrinology of female reproduction (Anti-mullerian hormone (made by…
Endocrinology of female reproduction
sexual dimorphism
sperm
constant fertility from puberty
300 million sperm produced per day
gradual decline with age
eggs
cyclical fertility - 3-5days a month from puberty
7 million follicles in utero - declines to 0 at menopause
400 follicles are ovulated
formation of the ovarian reserve
primordial germ cells colonise the gonad, numbers expand by mitosis, germ cells enter and then arrest in meiosis, primordial follicles form, folliculogenesis
meoisis pauses the resumes at ovulation - connections between chromones may need to be stable for 30-40 years - increased down syndrome risk with maternal age
follicle = reproductive unit of the ovary
primordial follicle - oocyte surrounded by squamous granulosa cells
primoridal follicle is recruited to grow and begcomes primary
primary follicle - granulosa cells become cuboidal and form 2 yarers - internal layer=zona pellucida
zona pellucida acts as a barrier
secondary follicle - theca layer between stroma and membrane properia - made from stroma cells with differentiate and coalesce on granulosa cells
early antral follicle - theca has differentiated into 2 layers
theca externa - acts as a protective fibrous casule
thec ainterna - contains blood vessels. gands etc - imprortant because the follicule is avascular
beginning of fluid-filled gaps secreted by granuosa- antral/follicluar fluid
ovulatory/antral/graafian follicle - all the fluid has coalesced into one big antrum whcih pushes the oocyte out - only attached by a thin stack of granulosa cells
one layer of granulosa cells adheres to outside of oocyte = corona radiata
cumulus cells - loosely associated with oocyte
Follicle selection
only one follicle is selected each month
oestorgen and FSH stimulate the expression of LHR - so whichever follicle has the most LHRs will be ovulated
optimum fertility at 23/24
cancer treatment can significantly effect reproducive lifespan
oxytocin
has major effects on smooth muscle contraction
milk ejection
contraction of the uterus during childbirth
used to induce labour
secretion is stimulated in response to stimulation of nipples of uterine distention
released during female orgasm
formation of mother-child bond
GNRH
gonadotropin releasing hromone
synthesised by hypothalamic neruones, the axons of which terminate on the portal system
pulsatile release - prevents receptor desensitisation and downreguklation
responds to ovarian hormonal feedback
water-soluble hromone - diffuse out at tagrte site, requires recpeotr binding because hydrophilic
GNRH, FSH, LH
oestrogen and progesterone = lipid-solulble - can freely diffuse into cell, atach to a binding protein in blood, receptors locatd in the nuslceus
gonadoptropin regulated follicle growth phase -
pre antral, early antral, preovulatroy follicle
FSH - antral granulosa cell differentiation, proflieration, funciton
LH - theca cell androgen production, ovulation
the gradual decline of primordial follicles is not affected by the endocrine system - pill only affects the larger follicles - gonadotropin regulated growth phase is inhibited
kisspeptin - integrates signals form many parts of the body as well as environmental cues
in arcuate nucleus
Anti-mullerian hormone
made by granulosa cells in the follicles
absent in primordial follicles, but present at later stages
inhibitory effect on follicle development
made in men to stop the foration of the female duct in the male reproductive system
unaffected by gonadotropins/steroid hromones - levels are only to do with the size of the follicles
reliable reflection of growing follicles
can be measured toindicate the number of follciles present in IVF
the menstrual cycle