Histo/Phys: female reproduction tract Flashcards
where are LH receptors?
theca cells
where are FSH cell receptors
granulosa cells
GnRH pulses???
1 GnRH pulse/hr = LH
1 GnRH pulse/3hr = FSH
what happens during follicular phase?
lasts first 14 days, same as proliferative phase
- slight surge in FSH is triggered by declining E and P levels. FSH stimulates cohort of follicles to mature from one ovary. Follicles produce a large amount of estradiol. Levels peak just prior to ovulation and result in a mid-cycle surge of LH through positive feedback loop. This LH surge stimulates ovulation.
What are the stages of ovarian follicle maturation?
- primary follicle with primary oocyte (46 cs, diploid 4n)
- primary unilaminar follcles: 1 oocyte rapidly grows
- multilaminar primary follcicles “granulosa cells”
4/5. secondary “antral follicle” - graafian mature follicle
what does primordial follcle contain?
primary oocyte
contains 46 css (diploid, 4N DNA) arrested in prophase of 1st meiotic division (and remain so for 12-50 yrs)
squamous follicular cells surround primary oocyte joined by desmosomes separated from stroma by BM
what is contained in primary unilaminar follcicle?
oocyte rapidly grows
follicular cells become cuboidal
zona pellucida begins to form, but not visible
zona pellucida - glycoprotein coat separates oocyte from follicular cells
multilaminar primary follicles?
follicular “granulosa cells” become multilayered these cells pass small precursor molecules to nurture oocyte
zona pellucida continues to develop
theca interna begins to be visible - differentiates from stroma around follicle
secondary antral follcicle?
antrum appears: hollow space
granulosa cells (follicular cells) continue to proliferate
synthesize & secrete estrogens (estradiol, estrone)
theca interna matures, theca externa begins to develop
Secondary follcile theca cells?
Theca interna developes in secondary follcile and cells become cuboidal. They develop features of steroid producing cell (synthesize testosterone and androstenedione under influence of LH, which is converted to estradiol and estrone via granulosa cells)
- separated from granulosa cells by well developed BM
- Theca externa begins to develop as CT arrayed around theca interna.
components of graafian mature follicle?
- antrum is enlarged and filled with liquor folliculi (contains steroid hormones, GAG’s and inhibin)
- zona pellucida is well developed
- cumulus oophorus = hillock of cells supporting the oocyte
- corona radiata = granulosa cells that surround the oocyte, these are retained with oocyte at ovulation and must be penetrated by sperm. They are reqd to transport ova in oviduct.
what causes ovulation?
high circulating levels of estrogen produced by granulosa cells results in positive feedback on FSH and LH. The LH surge leads to ovulation and the stigma ruptures elaborating oocyte (involves proteases such as plasmin)
- this results in a release of bloood and blood fills remaining follciular antrum, called corpora hemorrhagium
what happens at ovulation?
- primary oocyte completes 1st meiotic division to produce secondary oocyte (23 2n) and polar body
- after ovulation the oocyte is picked up by finbriae and enters infundibulum (oocyte is transported to uterus via peristalsis primarily and also by ciliary action)
- Oocyte enters 2nd meiotic division but is suspended in metaphase II until fertilization
- if oocyte is fertilized, it will finish second meitoic division and will produce an ovum (haploid 23, 1n)
ovulation vs. atresia?
ovulation usually produces single fertilizable oocyte, but a cohort of follicles form under FSH influence. 1 dominant follicle emerges about 1 week before ovulation
in follicular atresia: oocyte dies and antrum collapses. granulosa cells stop dividing, detach from basal lamina. during atresia some theca interna cells persist, make up “insterstitial glands” which secrete androgens through out life.
neonatal ovary?
primordial germ cells (oogonia) proliferate in genital ridges and continue to develop until they arrest in prophase I of meiosis (reached at 7th month of fetal life)
- fetus/neonatal ovaries show features of maturing and menarche
menarche?
establsihment of menstrual function
- at puberty pituitary gonadotropins increase leading to cyclic maturation of primordial follicles.
- during pre-pubertal period primordial follcilces being to mature though most are fated for atresia
400,000 follcicles at birth, only 150,000 follicles available at menarche
menopause?
cessation of menstrual cycle
- number of follicles becomes vanishingly small
- absence of follcicles
- theca interna cells remain producing androgens
What happens during luteal phase?
Corpus luteum formation occurs after ovulation and serves as the source of progesterone (peaks in the mid-luteal phase). Luteal hormonal output is dependent on LH and both FSH and LH levels decline to basal levels in the luteal phase (in part due to prodution of inhibin A). The corpus luteum will die in 14 days unless rescued by HCG from the implanted embryo.
What happens to corpus luteum during pregnancy?
- It persists and continues to produce high levels of estrogen and progesterone.
- it expands during pregnancy b/c of triggering from LH, but later LH starts to decline. Thus CL is maintained for 6 mos. by the hormone hCG.
during later stages of pregnancy CL secretes polypeptide hormone relaxin which increases pliability of pelvic CT and faciliates parturition.
What is corpus albicans
scar left after involution of CL. It will partially or completely involute with time.
What do estrogens do?
during puberty: stimulate growth of uterus and breasts and female fat disposition
menstural cycle: proliferation of endometrium
pregnancy: growth of mammary gland duct system, myometrial hypertrophy, increase in uterine blood flow
cellular effects: causes production of progesterone receptors
What does progesterone do?
puberty? minimal effect on breast growht
menstrual cycle: trophic effect on uterine glands, stimulates thick cervical mucous secretion
pregnancy: growth of mammary gland alveoli. impedes ovarian cycle by feedback to pituitary produced ovum - may serve as a homing signal to sperm
oviduct
uterine tube/fallopian tube
fn: fertilization usually occurs here, most commonly in the ampulla. Conveys oocyte to uterus for implantation, development and growth.
By day 4 the fertilized egg should be within the uterus
what are the portions of the oviduct?
- infundibulum: includes fimbrae - funnel shape with a ruffled fibria edge that envelops and sweeps over the ovary - complex folding
- ampulla: longest portion of tube that narrows as it enters isthmus. this is the most common site for fertilization to occur- complex folding
- isthmus - very little folding: small muscular tube
- intramural zone: tight portion that passes through myometrium of the uterus and is right before entry to uterus
What is estrogens effect on oviduct?
increases endosalpinx epithelial size increased blood flow to lamina propria increased oviduct specific glycoproteins increased ciliogenesis increased mucus, muscular tone of the isthmus
what does progesterone do to oviduct?
causes fertilization to be favored - decreased eptihelial size, increased deciliation decreased mucus relaxes muscular tone
what cells make up the epithelium of the oviduct?
simple columnar epithelium
- ciliated cells
- peg cells: mucous secretion cells that are tall columnar
what are the levels of the uterus?
1st layer: serosa/adventitia- forms laterally w/ broad ligament
2nd layer: myometrium - thick fibromuscular coat: middle layer is largest with circumferential fibers
3rd layer: endometrium: simple columnar epithelium with mixed ciliary and secretory cells that store glycogen. lamina propria is very thick and filled with blood vessels
what two layer does endometrium form?
pars functionalis: portion sloughed during menstruation
pars basalis: portion retained during menstruation - forms germinal tissue that renews pars functionalis
endometrial blood supply?
demarcates b/w the two endometrial layers
- arcuate aa. in myometrium supply straight aa. to the pars basalis. As the straight aa. move to pars functionalis they become coiled aa. The coiled aa. are heavily influenced by estrogen and progesterone levels. the estrogen and progesterone levels then are what drives the uterine cycle.
5 phases of uterine cycle?
- menstrual phase
- resurfacing phase
- proliferative phase
- secretory phase
- ischemic phase
what occurs during proliferative phase?
ovarian follicular phase
Reepithelialization of the basal layer
Estrogen drives cellular proliferation
Induces expression of progesterone receptors
what happens duirng secretory phase?
ovarian luteal phase Inhibition of endometrial growth Stimulation of uterine glands Changes to adhesivity of surface epithelium Opposes proliferative effect of estrogen
menstrual phase of uterine cycle?
occurs upon demise of CL
Coincides with early follicular phase
Upregulates MMPs
Upregulation of COX-2 (results in PGF2alpha) –> causes increased contraction of myometrium and closure of spiral aa.
when is basal body temperature high?
during secretory phase - occurs with increasing progesterone levels
histological menstrual phase?
(days 1-5) = sloughing of functionalis occurs at the end of ischemic phase.
- WBC’s and MO’s invade stroma of functionalis
- coiled aa. become compact –> function layer blanches/necroses, damaging arterioles and microvasculature
- blood accumulates in stroma: epithelium ruptures
- coiled aa. constrict hemorrhage
- menstrual flow contains unfertilized secondary oocyte
- prostaglandins secreted (i.e. PGF2alpha) causes myometrial conractions (cramps) and is a potent vaso-dilator leading to water retention.
histological resurfacing phase?
- days 5-6
epithelial cells from base of glands proliferate migrate to resurface endometrium angiogenesis begins- vascular channels begin to rebuild
histological proliferative phase
- days 7-15
basalis grows and renews functional layer under influence of estrogen - late in phase endometrium has thickned, glands are strait and long and project into lumen, glycogen has been accumulated in basal portion of epithelium, coiled aa. have grown toward surface
histological secretory phase?
days 15-26
- functionalis continues to thicken: glandular epithelium become tall and are filled with secretory product
- coiled aa. extend to upper surface of endometrium
- Progeterone results in coiling of glands
- glycogen moves to apical region of eptithelial cells and gives the ragged appearance
- fluid accumulates in interstitium
histologic ischemic phase?
days 27-28
- Estradiol and progesterone levels fall: low levels can no longer support functionalis.
- glands become very coiled and tortuous, causing interuption of blood supply.
- endometrium shrinks and functionalis degenerates
- prep. of onset of menses
histology of the cervix?
- differs from rest of uterus in that there is little smooth muscle in wall (easy for cervical wall to expand, because has more fibers)
- extensive ense CT which degrades (collagenolysis), leading to cervical dilation
- surface lined with: simple columnar eptiheltium, contains mucosa secreting cells but no coiled aa. it does not slough during menstruation
- stratified squamous appears at external uterine os
what do cervical glands produce?
- thin watery mucous that allows sperm access to ovum. after ovulation it becomes thick and inhibits foreign material from entering uterus
- glands produce under influence of estrogen, thin watery and slightly alkaline mucus
- under influence of progesterone: they produce scant, viscous, slightly acidic mucous that forms the cervical plug
what is vagina composed of?
stratified squamous wet epithelium that is thrown into transverse folds (ruggae)
- thickest during mid-cycle at estrogen peak
- Langerhans cells are present to serve an APC fn
- no glands: mucous derived form cervical glands
what maintains acidic pH of vagina?
surface layer cells are flat and accumulate glycogen at mid-cycle. These cells desquamate and release glycogen which is the subsrate for the acid forming bacteria resulting in pH of 3.8-4.5
- a fall in estrogen levels reduces stored glycogen, and vaginal pH becomes more alkaline, favoring sperm survival and infectious organism proflieration
what is vaginal mucosa composed of?
Lamina propria: wide band of dense fibrous CT, elastic fibers present towards lumen, outer region very vascular
- contains diffuse lymphocytes/nodules and WBC’s invade epithelium during menses
- no general sensory receptors in vagina, primary sensory nerves are nociceptors.
what is the muscularis layer of vaginal mucosa composed of?
2 indistinct smooth m. layers:
- inner layer: circular orientation
- outer longitudianl layer
- skeletal m. surrounds vaginal introitus
labia majora
homolog of male scrotum
composed of : skin, hair appears at puberty and adipose tissue
labia minora
stratified non-keratinized eptihelium
lamina propria is highly vascular
contains numerous papillae
sebaceous glands are present but no hair follicles
melanocytes are present and it is highly pigmented
vestibule
similar to vagina, except mucous glands are present
major mucous glands:
- vestibular glands (glands of bartholin) - homolog of bulbourethral glands in males
how do hormones affect the vagina?
estrogen: stimulates proliferation of vaginal epithelium and increases glycogen content
progesterone: increases the desquamation of epi. cells
glycogen: metabolized to lactic acid by commensal lactobacilli - maintains an acidic enciron. and prevents infection
what are the system effects of estrogen/progesterone? Bone, liver, Cardio, CNS?
Bone: estrogens promote closure of epiphyseal plates and anabolic/calciotropic effect
Liver: Estrogens increase LDL receptor, HDL levels, CBP, THBP, sex hormone - BP
CV: estrogens cause vasodilation through NO synth
CNS: estrogens are neuroprotective. progesterones regulate set-point for thermoregulation
