Mammalian reproduction control by Hormones Flashcards
wall of uterus (from external to internal)
perimetric, myometrium, endometrium
endometrium
Varies with the menstrual cycle
cervix
an extra-thick layer of muscle at the bottom of the uterus to hold the opening closed
uterine horns
present in mammals that have litters. They will have implantation all along the uterine horn.
corpus luteum
forms from the follicle cells that reorganize after the oocyte is ejected from the ovary. Corpus luteum secretes estrogen and progesterone. When the corpus luteum breaks down, estrogen and progesterone are not being secreted anymore. Progesterone maintains wall of uterus, so when the corpus luteum breaks down, the uterine wall begins to slough off –> period.
follicle cells
Grow around oocyte and secrete estrogen
corpus albicans
forms from the corpus luteum breaking down. Corpus albicans is scar tissue. When corpus luteum breaks down to corpus albicans, it stops producing estrogen and progesterone.
pituitary gland
secretes LH and FSH
LH
luteinizing hormone - secreted by pituitary. Spike in LH causes ovulation.
FSH
follicle stimulating hormone - secreted by pituitary. Tells primary follicles to grow. As follicle cells grow, they secrete more estrogen, which causes the thickening of the endometrium.
LH and FSH affects on menstrual cycle
FSH causes follicle cells to develop. LH causes ovulation.
follicular phase
the phase of the menstrual cycle when the follicle is developing. More estrogen is produced than progesterone during this phase.
ovulation
marks the end of follicular phase and beginning of luteal phase. Caused by spike in LH.
luteal phase
controlled by actions of corpus luteum. At the beginning of this phase, estrogen dips while follicle cells are reoraganizing. Then estrogen and progesterone are produced by corpus luteum.
estrogen
responsible for preparing wall of the uterus; cell division, vascularization
progesterone
maintains wall uterus. The fall of progesterone when corpus luteum becomes corpus albicans signals the uterine wall to start sloughing off - period ensues.
hormone feedback
corpus luteum releases estrogen and progesterone, which feed back to the hypothalamus to prevent the release of FSH and LH
HCG
Human chorionic gonadotropin.
If the egg has been fertilized by the sperm, HCG rescues the corpus luteum. (When corpus luteum degrades, progesterone stops being produced, which leads to the uterine wall sloughing off.) If progesterone and estrogen continue to be secreted, the wall of the uterus will continue to be maintained.
estrous cycle
The other type of cycle used by mammals (instead of menstrual cycle).
Key characteristics:
- -shorter luteal phase, so there is less endometrial buildup, so no menstruation
- -Period of heat
a. monestrous cycle - only one period of heat every year (e.g.. deer)
b. polyestrous cycle - multiple periods of heat every year (e.g. rabbits)
marsupial reproduction
- -shorter gestation
- -longer lactation
- -embryonic diapause
- -Marsupials are less developed at birth due to shorter gestation period.
- -Embryonic diapause –> kangaroos can carry 3 babies at 3 different stages of life at once
ways to have twins
- fertilization of 2 different oocytes–> 2 embryos in the uterus (fraternal twins)
- Single oocyte splits –> identical twins
a. can happen early in development so the embryos develop their own sac
b. can happen later in development so embryos share the same sac
c. can happen so late that the inner cell mass doesn’t completely split and then you get Siamese twins
placenta
forms from the outer chorion and syncytiotrophoblast cells.