o The cow's cervix has 4-5 annular rings and a fornix vagina
o Cows have a bicornuate uterus: one cervix, one uterine body, one vagina, and medium size uterine horns. The fetus will grow in the uterine horns.
o Humans have a simplex uterus: there is one cervix, one vagina, and one large uterine body. Humans do not have uterine horns, so the fetus will grow in the uterine body.
o Cows also have caruncles on the endometrium where the cotyledons of the placenta attach. These cotyledons surround the entire placenta.
o Humans have a discoid placenta where the points of attachment are on one side for gas, nutrient, metabolic, and waste exchange occur.
o The cow has a labia majora (external vulva) where the human has a labia majora and minora (external vulva)
o In cows, the CL secretes progesterone to maintain pregnancy. If pregnancy does not occur, then the CL regresses. CL regression is caused by prostaglandin secretions from the uterine horn ipsilateral to the CL. The posterior pituitary and the CL release oxytocin which triggers the uterus to release prostaglandin which causes regression of the CL (Luteolysis).
o In humans, the CL secretes progesterone and estrogen. The CL in the human lasts for 12-14 days and if the person is not pregnant, then the CL self-destructs. The CL needs h CG to maintain pregnancy.
o Cows have an estrus cycle and humans have a menstrual cycle.
o Estrus cycle:
• Proestrus: follicle enlarges, E2 increases
• Estrus: allows males to mount, ovulation 24-48 h after LH surge
• Metestrus: low E2, ovulation in cow, corpus hemorrhagicum, FSH increases
• Diestrus: fxnal CL and secretes progesterone, FSH growth of ovulatory follicle, CL regresses if not pregnant and repeat
o Menstrual Cycle:
Menses: blood tissue secretions out of uterus and into vagina, recruitment of follicles
Follicular Phase: about 9 days, the development of dominant follicle, E2 AND P4 increases, LH surge
Luteal phase: CL, high P4 and E2, regression of CL and repeat
o Ovulation over entire surface of ovary
o Same outcome: a baby