The Menstrual Cycle Flashcards
Which phase is first, follicular or luteal?
Follicular
Ovulation occurs _____________.
between the follicular and luteal phases
How much sperm is produced per unit time?
Roughly 1,000 / second
Describe meiosis I and meiosis II in females.
Meiosis I is highly asymmetric: it produces the first polar body and a 2n oocyte.
Meiosis II is also highly asymmetric: it produces the second polar body and the fertilizable oocyte.
The flat cells lining the border of the germ cell nest are _____________.
pregranulosa cells
Originally, more _____________ enter the germ cell nest, but most die prior to gestation.
oocytes
In which part of meiosis do female germ cells pause?
Prophase I
Primordial follicles are composed of ______________.
primary oocytes and 1-5 pregranulosa cells per follicle
In terms of oocytes, what is the antrum?
It is the vacuole-like area around the granulosa cells.
What is needed to produce estradiol?
Large growing follicles containing eggs
Progesterone is made from ____________.
pregnenolone catalyzed by 3-beta HSD
________________ supports the corpus luteum.
hCG produced by the placenta
Presence of the _____________ prevents luteinization.
egg (thus, ovulation has to occur)
Meiotic resumption occurs due to _______________.
paracrine and endocrine signals
The follicle with the most ____________ will be the one that is ovulated.
FSH receptors, LH receptors, estrogen, aromatase, and 17-alpha
What causes the switch from negative to positive estrogen feedback?
Rapid rise of estrogen; if estrogen rises slowly, then it maintains negative feedback
Body temperature is higher in the ______________ phase.
luteal
The slow rise of estrogen causes _______________.
a switch to positive feedback in the gonadotropic hormones LH and FSH which causes ovulation
True or false: the 2 chromosomes present in cells after meiosis I are identical.
True.
Primordial follicles do not grow until _____________.
puberty
Antral follicles have large _______________.
cleared out areas
Going through the layers in a maturing oocyte from inside to outside, you’ll pass through ________________.
antrum, granulosa, basement membrane, theca internal, and theca external
What is the one hormone that rises during the luteal phase?
Progesterone (produced by the corpus luteum)
Note: estrogen does have a slight bump, but its overall trend is downward
Where does progesterone come from?
The corpus luteum
It produces progesterone autonomously immediately after ovulation. If fertilization takes place, then placental hCG will stimulate the growth of the corpus luteum throughout pregnancy.
FSH specifically stimulates _____________.
granulosa proliferation
LH specifically stimulates ______________.
conversion of the granulosa cells to luteal cells
The ______________ stage comes after the proliferative stage.
secretory (14 days)
Each ovulatory cycle, there are about _________ oocytes that get recruited for potential ovulation.
30
True or false: recombination occurs during fetal life.
True.
Recombination occurs during _________.
metaphase I
The ___________ phase is more consistent in its timing.
luteal
Primordial, primary, secondary, tertiary, and Graffian follicles all contain ___________.
primary oocytes
What histologic feature distinguishes primordial oocytes from primary oocytes?
The zona pellucida glycoprotein layer
What distinguishes a primary oocyte from a secondary oocyte?
Secondary oocytes have more cuboidal granulosa cells; also, theca cells develop around the periphery
Where is the oocyte basement membrane?
Between the granulosa cells and the theca interna
The corona radiata is made of ___________ and surrounds ___________.
granulosa cells; the zona pellucida
Meiosis I finishes just prior to ___________.
ovulation
Why does the corpus luteum need such an abundant blood supply?
Because it needs LDL to make progesterone
How does inhibin B help select only one follicle?
The follicle that is dominant will secrete inhibin B which will decrease the amount of FSH secreted (which would limit the other follicles from developing).
What distinguishes Graafian follicles from tertiary follicles?
Graafian follicles have oocytes on stalks and are much larger.
