The Ovarian Cycle

Hypothalamic-Pituitary-Ovarian Axis

The Follicular Phase

HYPOTHALAMUS GnRH ANTERIOR PITUITARY FSH LH OVARY Follicle Estrogens

Follicle Stimulating Hormone (FSH) Stimulates growth of follicles Follicles produce ESTROGEN (Estradiol)

Follicular Development

OVULATION

OVULATION A human egg is caught on camera as it emerges from a woman’s ovary. It is one in a series of the clearest ever images of the ovulation process and was accidentally snapped by surgeon Jacques Donnez, of the Catholic University of Louvain in Brussels, as he performed a hysterectomy. The yellowish egg (about the size of this dot ·) is seen exiting a red, fluid-filled follicle on the surface of the 45-year-old woman’s ovary. Ovulation took a full 15 minutes — much slower than the sudden ‘explosive’process suggested by some theories. Although human ovulation has never been seen in such detail before, it is a process that occurs at least once a month in fertile women. On release, an oocyte travels along a fallopian tube to the uterus. These rare images, which appeared in New Scientist magazine last week, will be published in the journal Fertility and Sterility (J.-C. Lousse and J. Donnez doi:10.1016/j.fertnstert.2007.12.049).

Ovulation

The Luteal Phase

What is Estrogen Doing? Stimulates growth of cells in the lining of the uterus, the cervix and the vagina Causes breast to be more receptive to progesterone Causes changes in cervical mucous

Changes in Cervix and Cervical Mucous Around ovulation: Cervix opens Fibers line up under influence of estrogen permitting sperm to get through

Changes in Cervix and Cervical Mucous After ovulation Cervix closes Fibers of mucous tangle up

What about Progesterone? Secreted by the Corpus Luteum after ovulation

What about Progesterone? Helps with the functioning of lining of the uterus (in preparation for fertilization) Prepares breasts for possible pregnancy Signals the pituitary to stop producing LH

What Triggers Menstruation? No fertilization Corpus Luteum regresses after about 12 days Progesterone & estrogen products drop off sharply Endometrium sloughs off

What happens if fertilization does occur? Corpus luteum remains active Progesterone levels remain high  uterine lining remains strong Implantation occurs hCG from fetus takes over

What is the hormonal signature of the…. Follicular phase Low E, low P High E levels, low P levels High P levels High LH, decreasing E, low P

What is the hormonal signature of the…. Luteal phase Low E, low P High E levels, low P levels High P levels High LH, decreasing E, low P

What is the hormonal signature of the…. First day of menstrual bleeding Low E, low P High E levels, low P levels High P levels High LH, decreasing E, low P

What is the hormonal signature of the…. Peri-ovulatory period Low E, low P High E levels, low P levels High P levels High LH, decreasing E, low P