Lecture 3 & 4 - Oogenesis Flashcards
Oogenesis Process
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How is oestrogen made?
Made from progesterone –> angrogens –> to oestrogen
- get androgens made in thecal cells, then graunulosa cells convert the androgen to oestrogen
- FSH will stimulate oestrogen to be made
What is important about zona pelluicida
important blocking entry of sperm after fertilisation (dont want too many chromosomes)
- ZP1 - in primordial follicles
- ZP2, 3 - added to activated follicules
Why is amh hormone important?
This stops the progression from primidoral to primary follicule development
- AMH conc is related to the number of follicules a women has remaining
- can use this as an indicator of fertility (“follicular reserve”)
Differences in Primordial follicule, primary follicule, secodnary follicule and tertiary follicule, corpus leuteum, corpus albucis
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If the follicule has an antrum what is it calssified as?
tertiary follicule!
What happens when there is an increase in progesterone?
increase in basal body temp - can be used for female planning conception ect.
Hormones involved in the ovarian cycle
Diagram
- Day 1 - menstration
- increase in estrogen as follicules develop (released in response to fsh)
Negative Feedback - there is negative feedback of oestrogen back to the hypothalamus to stop gnhr, fsh and lh - so get a drop in fsh
Positive feedback - when you get an increase in eostrogen to a certain level, then get will get positive feedback and lh will be produced.
LH - will increase after positive fedeback of estrogen, then will act of follicule to induce ovulation - this will occur 24 hours after the peak at around day 14
Progesterone - is produced by corpus leteum and continues pregnancy
Why do we work backwards from menstruation
Luteal phase is more constant than follicular phase in women
- follicular phase then luteal phase
- on av 28 days cycle
Fallopian tube structure
- names
- epithelium
- muscular layer
fibrae, infundibulum, ampulla, isthmus
- ciliated and secretory epithelium
- ICOL - muscle
- serosal coat
WHat do oestrogen and progesterone stimulate in the fallopian tubes?
Estrogen - increase cilia, secretory activity, muscular activity (allow sperm and egg to move, and for nutrtion)
Progesterone
-decrease muscular actiivty, comule of secretions, and increases beat frequency - helpful in motion of embreyo
Structure of uterus lining?
Endometrium - functional layer, what changes and is lost during mestral cycle
basal layer - uncahnged
Myometrium - for forecefull expulsion of fetus
-stays constant
Desidual reaction - prepares lining for implantation
-stroma of endometrium becomes odematious, stromal fibroblasts expand and fill w glycogen and this is an energy source for embreyos.
Why are the spiral arteries coiled? how to stop bleeding when menstruation
Large amount of growth going to occur in the endometrial layer
- need a large blood supply to supply this
- rather than having to make new blood vessels during pregnancy, they are already coiled so can just straighten out.
- they form spirals becasue tehy grow faster than the surroundign stroma
spiral arteries undergo spasm
Estrogen and progesterone in the uterus
Estrogen - stimulates
epithelial and stromal cell proliferation stromal oedema
glandular secretions (serous)
synthesis of intracellular progesterone receptors (estrogen priming)
myometrial activity
Progesterone stimulates:
• glandular secretions (thick) in luteal phase (against an oestrogen background)
• stromal cell proliferation Progesterone inhibits:
• myometrial activity
Why do you not always need a decidual reaction for pregnancy?
ectopic prengnacy - not in uterus
Ectopic pregnancy
- Most commonly fallopian tubes
- pregnancy not in the uterus
Endometriosis
- chronic pelvic pain
- associated with infertility
- it is endometrial tissue outside the utereus
- unsure causes - retrograde menstruation - not all of it gets exited out of vagina
HPV
target zone where endocervis - columnar epothelium transision to ectocervix - stratified squamous epithelium
Changes in cervical mucous across menstrual cycle
start - estrogen stimulates an increase in volume and a decrease in viscosity around the midcycle
- this is to allow sperm to penetrate easily
- Then Progesterone stimulates a highly viscous and cross-linked mucous that is a barrier to sperm penetration
Where do oocytes originate from?
Primidoral germ cells in the yolk sac
What structure is in the tertiary follicule ?
Cumulous oophoros
- combination of oocyte w granulosa cells
- has a bit of weakness around it - in ovulation, this structure will break, and ooctye will be free to be released out of follicule and ovary
- have cumulus oocyte coplex
- tertiary follicules press up right agianst this and then ovulation occurs when wall is weakend and broken down
Hormones released at hypothalamus, anterior pituiatry what is target organ and what does this produce
- GnRH
- LH/FSH
- Tests/ovary
- Estrogen/testosterone
What cells are in the corpus leteum
cells left behind after oocyte has been released
-start to rapidly proliferate into
-Lutenised granulosa cells
lutenised theca interna cells - produce progesterone (also estrogen)
-are repsonsive to LH
Corpus albucins will form - this is scar tissue
Uterine cycle - menstrual cycle - phases and hormones invovled
Menstration - estrogen starts to build up
proliferation - estrogen wil help build up the lining - promotes growht
Secretory phase
Progesterone - induces the decidual reaction - ready for implantaiton, and also renders cervial mucous permissive to sperm transport
