Menstrual Cycle and IVF
What are the two cycles called?
Ovarian and uterine
Ovarian: Controls production and release of eggs and cyclic release of oestradiol and progesterone.
Uterine: Controls preperation and maintenance of the lining of the uterus to recieve a fertilized egg.
What is the purpose of the menstrual cycle?
To time the release of an egg (ovulation) for possible fertilization and later implantation into the lining of the uterus. This implantation must occur when the uterine inner lining (endometrium) is rich with blood vessels.
What is the hypothalamus and what does it produce?
Hypothalamus is the regulatory center for the menstrual cycle. Produces gonadotropin releasing hormone (GnRH)
Which two hormones does the pituitary gland produce?
Follicle stimulating hormone (FSH) and lutenizing hormone (LH)
What is the target issue of FSH and LH?
The ovaries
What is the target tissue of oestradiol?
The endometrium
Oestradiol stimulates the pituitary gland to release more FSH and LH. This an example of positive or negative feedback?
Positive
When oestradiol reaches high levels it inhibits the secretion of FSH and LH. This is an example of positive or negative feedback?
Negative
What does a spike in FSH and LH lead to?
Ovulation
LH rises stimulating the completion of _____ in the oocyte and partial digestion of the _____, allowing it to burst open at ovulation. LH also promotes the development of the wall of the _____ after ovulation into the _____ which secretes oestradiol and _____.
Meiosis, follicle wall, follicle, corpeus luteum, progesterone
Progesterone reaching a peak then dropping back to a low level indicates the end of the _____ cycle.
Uterine
What does progestrone do?
Promotes the thickening and maintenance of the endometrium. Also inhibits FSH and LH secretion by the pituitary gland.
If the oocyte is not fertilized, what happens?
It breaks down and leads to a decline in oestradiol and progesterone. A drop in these hormones causes the endomtrium to rupture and menstruation occurs.
High levels of progrstrone and oestradiol at the same time provide a negative feedback signal to the hypothalamus and prevents the production of _____. What happens as a result?
GnRH
As a result, FSH and LH levels remain low.
What are the two ovarian hormones produced by the wall of the follicle and corpus luteum?
Oestradiol and progesterone
FSH rises to a peak during the _____ cycle. It also stimulates the development of ______. It also stimulates the secretion of oestradiol by follicle wall.
Ovarian, follicles