female urogenital system Flashcards
number of oocytes at puberty
200,000
number ovulated
400
ovary size
almond
cortex contains
germ cells in follicles
medulla contains
vessels, nerves and some steroid-secreting cells
interstitial tissue between follicles (stroma) contains
corpus luteum
corpus albicans
derived from previously ovulated follicles
blood supply
ovarian artery from aorta
drainage to IVC
ovary position
intraperitoneal
attached to the posterior aspect of the broad ligament by the mesovarium, through which vessels and nerves enter
ovary major functions
cyclic production of haploid gametes
production of hormones to coordinate the body for successful reproduction
before birth cell stage
primary oocyte arrested in prophase 1
build up stores of RNA and protein and rest until puberty
cell stages at puberty
go through meiosis 1 to make a secondary oocyte, stops at meiosis 2 (cytoplasm doesn’t split evenly, so only one main cell is produced)
other cell becomes first polar body and degenerates
after the secondary oocyte is produced
secondary oocyte is arrested in metaphase 2 and then ovulated
meiosis 2 only completed if fertilised, producing another polar body
follicle structure
each follicle has an oocyte with one or more layers of specialised cells and their products
granulosa cells function
become more cuboidal in development
equivalent to sertoli
production of steroids (estradiol) and LH receptors
has basal lamina around cells (no blood vessels can pass through)
zona pellucida function
glycoprotein rich layer around the oocyte, secreted by oocyte and has sperm receptors at fertilisation
theca cells function
on outer surface
inner secrete steroids (produce androgen substrate for estradiol production)
outer layer from a capsule, highly vascularised
layers around primordial follicle
just early granulosa cells
layers around primary follicle
mature granulosa cells with basal lamina
layers around secondary follicle
mature granulosa cells and thecal cell layers
follicle development depends on
FSH
in secondary follicle, granulosa cells are signalled to
secrete fluid between the granulosa layers to produce an antrum (tertiary follicle)
dominant pre-ovulatory follicle selected, causing
large antrum to form, separating the granulosum cells into those around the wall and those around the oocyte
primordial follicles recruited to start folliculogenesis until
menopause
what occurs between the tertiary follicle and the preovulatory follicle
follicle growth
recruitment
selection
dominance
mature follicle structure
fluid filled antrum, large
oocyte, pushed to one side surrounded by 2 or 3 layers of granulosum cells (called cumulus oophorus)
what its follicular atresia
about 20 follicles mature each month but only 1 is ovulated
rest undergo atresia (hormonal apoptosis)
control of menstrual cycle
hypathalamo = pituitary - gonadal axis
LH and FSH release
from gonadotrophs in pituitary
controlled by pulses of gonadotrophin releasing hormone (GnRH) from hypothalamus
GnRH control
neuronal hormone kisspeptin
negative feedback on pituitary and hypothalamus
progesterone
oestrogen
inhibin (peptide for neg feedback of FSH)
two cell two hormone mechanism
thecal and granulosum cells
and FSH and LH both need to be stimulated by GnRH for ovary function
action of LH in ovary
acts at LH receptors on theca interna cells to stimulate the production of androgens via cAMP
action of FSH in ovary
at FSH receptors on granulosa cells to produce aromatase which converts androgens to estradiol and inhibin
phases of the menstrual cycle
follicular phase and luteal phase
length of cycle
28 days
starts on first day on menstruation
length depends on follicle growth and lifespan of corpus luteum
follicular phase dominated by
the products of a single dominant follicle
luteal phase dominated by
products of the corpus luteum
follicular phase - action of estradiol and inhibin
- inhibit FSH release, so select a dominant follicle
follicular phase - action of rising estradiol
- estradiol from dominant follicle stimulates the pre ovulatory surge of LH and FSH
- sensitises the pituitary to GnRH, causes GnRH to stimulate a surge of LH
surge of LH causes
acts on LH receptors of granulosa cells of dominant follicle to cause ovulation and complete the first meiotic division
ovulation process
takes 15 min
oocyte ruptures out of follicle
- induced by LH
- through cAMP, promotes production of prostaglandins and plasminogen
- collagen breakdown weakens follicle wall
- vascular permeability
luteal phase - what forms the corpus luteum
remaining granulosa cells and thecal cells from ruptured follicle
effect of LH surge on blood vessels
ingrowth of blood vessels through the basal lamina
changes in enzymes so that progesterone dominates
progesterone and estradiol production after ovulation
increases for about 7 days
stimulated by slow LH pulses
hCG produced if
fertilisation and implantation occur
no hcg = corpus lutetium degenerates
luteolysis causes
progesterone and oestrogen levels fall
negative feedback of FSH and LH removed so follicle development stimulated
main function of corpus luteum
secrete progesterone
function of oviduct
high estradiol at the end of follicular phase and in luteal phase cause muscular activity in the oviduct
causes its end to become closely opposed to the site of ovulation, ciliated epithelium wafts the oocytes into the tube
secretions from epithelial ells help nourish the oocyte
uterus in menstrual cycle
progesterone and oestrogen produce changes in uterine all to prepare for implantation
uterus in early phase of cycle
endometrium relatively thin
oestrogen causes it to expand and develop
sparse and small glands
cells develop microvilli and cilia
uterus in secretory phase
begins at ovulation
glands become more coiled and endometrium has maximum thickness
uterus changes in vasculature
arteries become more extensive and more spiralled through proliferative phase
during late secretory, walls become more ischaemic as arteries spasm, under control of prostaglandins to prevent excessive blood loss
hormone control of uterus
estradiol = proliferation and spiral artery development progesterone = glandular secretion prostaglandins = arterial spasm , uterine muscle spasm
hormone release pre/post puberty
pre = GnrRH fires occasionally, low secretion of LH/FSH post = GnRH neurons fire about every 90 min, pulses of FSH and LH
what happens at menopause
oocytes = 0
secretion of oestrogen and inhibin reduced
lack of negative feedback = FSH and LH increase
blood supply to uterus
internal iliac artery and vein
