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What controls the follicular phase?
What controls the Luteal phase?
During hte follicular phase, what does FSH cause?
- Causes several immature follicles to become active
- Also causes these follicle cells to produce and secrete estrogen (estradiol and progesterone)
- Causes the primary oocyte to reinitiate meiosis
FSH does what to the immature follicles and why?
what does this mean?
- Reactivates (remember at birth, they stopped. The primary oocyte was in prophase I)
- a. This means that the follicle cells surrounding the potential gamete proliferate by mitosis
a. Only one follicle will mature, but we have several starting to mature. Why? What happens to the rest that start and don’t mature?
- i. Why several mature is so that sufficient estrogen will be produced to be used in the menstrual cycle
- 1. You need several follicles to start maturing to ensure sufficient levels of estrogen being produced
- a. Estrogen used in menstrual
At some point in this follicular phase, when __ are __ and can be used in the __, then what happens.
i. then all but one of the reactivated follicles die
- high enough (sufficient)
- menstrual cycle
What is the function of activating multiple mollecules at the beginning of the ovarian cycle?
a. to produce sufficient estrogen because one would not do it
What happens to the dead follicles? What do they represent?
- look like little pieces of white scar tissue= corpa albicantia (white bodies)
- 1. Represent the reactivated follicles each month that died; that never made it to maturation and died
What happens to one immature follicle?
- i. matures
- 1. Primary oocyte in that mature follicle completes meiosis I and begins meiosis II (arrest= needs sperm to be reactivated)
Movement of the follicle at the mid-ovarian cycle?
a. Follicle moves from about the center of the ovary to the periphery of the ovary because it will allow it to leave more easily (mid-ovarian cycle)
In terms of estrogen, what happens mid-cycle?
- a. estrogen levels are normal high
- i. These high estrogen levels act on the anterior pituitary and cause FSH to be turned off and LH to be turned on
- 1. High estrogen levels turn off FSH and turn on LH= surge of LH mid-cycle due to estrogen levels
In the luteal phase, what is LH responsible for?
- i. ovulation, which is the spewing of the secondary oocyte and some of its surrounding follicle cells from the ovary
- 1. Pushes the inner layers of follicle cells out with secondary oocyte
- a. Causes Graffian follicle
What else does LH cause?
- i. Also causes the healing of the ruptured follicle (Graffian) to form the corpus luteum (the yellow body)
- 1. Which are the follicle cells that remained in the ovary after the oocyte and some of its follicle cells are released
- 2. Extremely important body
After healing the corpus luteum, what does LH cause it to do?
In terms of the corpus luteum itself, what does LH do?
- i. causes the corpus luteum to produce and secrete mainly progesterone
- ii. Maintains the corpus luteum
- 1. It keeps it alive
When would pregnancy occur?
around ovulation maybe around day 14 or 15
What happens if no fertilization occurs? Effects?
- i. high progesterone turns off LHà corpus luteum dies and becomes a corpa albicantia
- 1. If the corpus luteum dies, there is no more production of progesterone and progesterone levels decrease (consequence seen in menstrual cycle)
If there is a pregnancy, what happens? What are we left with?
- i. Toward the end of the cycle, high progesterone turns off LH
- 1. But now we have an embryo that is approximately two weeks old and the embryo is secreting HCG (human chorionic gonadotropins)
What does HCG do?
- a. It takes up where LH left off
- b. It maintains the corpus luteum during the first trimester
- c. Keeps the corpus luteum producing and secreting progesterone DURING THE FIRST TRIMESTER
- d. HCG levels are responsible for morning sickness, which occur at first trimester
- i. HCG found in urine and blood for pregnancy tests
When does the corpus luteum die? What happens?
- 1. Corpus luteum dies at end of first trimester, but PROGESTERONE LEVELS DON’T DECREASE
- a. It’s being produced and secreted by the placenta
- i. It takes about the first 2-3 months for the placentum to mature and produce hormones
What happens if progesterone levels decrease too soon?
a. If progesterone levels decrease too soon, it can result in a spontaneous abortion
Where is the egg after it is dispelled?