Lecture 7 - Female Reproductive Physiology Flashcards
What are the main components of an ovary?
- Stroma (most of it)
- Corpus luteum (that regresses)
- BVs
- Primary follicle –> secondary follicle –> mature follicle – ruptured follicle
What do LH and FSH act on in the hypothalamic-pituitary-ovarianaxis?
LH: endocrine cells (which produce steroid and peptide hormones) –> gamete production
FSH: gamete production
What are the two monthly cycles that happen in female?
Ovarian cycle & uterine cycle
What are the stages of the ovarian cycle? How long does each go for and what hormones are highest in each?
- Folicular stage ~ 14 days –> granulosa cells increasing oestrogen secretion (because of increased FSH & then increased LH to complete the growth). Here the granulosa cells also secrete AMH which prevents any more follicles from developing.
- Ovulation - FSH & LH & oestrogen at their peak. LH is the highest because it is not affected by inhibin.
- Luteal stage ~ 14 days –> oestrogen still high but a slight drop - very high inhibin & progesterone for negative feedback to stop LH & FSH secretion
What are the stages of the uterine cycle? How long does each go for and what hormones are highest in each?
- Menses ~ 7 days - shedding lining. All hormones low but estrogen highest.
- Proliferative phase ~ 7 days - getting thicker. Estrogen going up here and starting to spike.
- Secretory phase ~ 14 days - thickest. All high, progesterone & inhibin highest.
What happens to the corpus luteum if pregnancy occurs? Does not occur?
Occurs = it is maintained
Does not occur = it degenerates and dies after 12 days
What changes occur from day 1 of pregnancy to day 6?
Day 6: microvilli are lost on apical surface (there are lots there on day 1), these microvilli impair attachment, more tight junctions extend down deeper on lateral surface, focal adhesions on basal surface are lost.
What are the three phases of receptivity of the uterus to blastocyst implantation?
- Pre-receptive phase - microvilli shortening
- Receptive phase - microvilli continuing to shorten
- Refractory phase
What happens to integrins when the uterus goes from non-receptive to receptive?
- Originally on basal surface (integrins alpha & beta) connecting the cells to the ECM
- When receptive they all move up to the apical surface of the cell
FOCAL ADHESION DISASSEMBLY - The embryo secretes ECM proteins (fibronectin) and the integrins help to attach it to the apical surface of the uterus
Within the follicular stage of the ovarian cycle meiosis stops and starts at different stages? When is this?
- Meiosis arrests while the follicle goes from primordial to primary to secondary
- FSH increases
- LH surge
- Meiosis continues during Maturation 1 (M1) and PB1 (polar body 1)
- Meiosis arrests again during M2 when the mature oocyte is reading for fertilisation
What type of signalling occurs between the oocyte & follicle? Why is this important?
- Important signalling from granulosa cells to oocyte but also the other way around - PARACRINE SIGNALLING
- Required for the normal growth & development of both the oocyte & the follicle
What are the cumulus cells? What is the COC? Why is communication between it and the oocyte important?
- A cluster of cells that surround the oocyte both in the ovarian follicle and after ovulation. Collectively known as the cumulus-oocyte complex.
- Studies show that removing the oocyte results in increased apoptosis of the cumulus cells, therefore suggests the oocyte is secreting a factor that is preventing apoptosis and prolonging the life of the cumulus cells
What is important about oocyte-secreted factors (OSFs)?
They enhance oocyte developmental confidence
What is aneuploidy?
- The presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46.
- Can be caused by nondisjunction in the 1st or 2nd meiotic division.
What is monosomy and what is trisomy? What is an example of a syndrome of each?
M: Turner syndrome - 45 X karyotype - only monosomy compatible with life
T: Down syndrome - A.K.A. trisomy 21
