Progesterone also promotes complete development of the alveoli of the mammary gland. Estrogens - These hormone are a group of compounds produced primarily by cells of the ovarian follicles, however they are also produced by the placenta and adrenal gland. They stimulate development and functioning of the female reproductive tract. Estradiol, one of the estrogens, is the hormone primarily responsible for the symptoms of estrus. The maximum concentration of estradiol is found around estrus.
Estrogens also initiate growth and development of the mammary gland ducts.
This hormone is produced by the ovaries to cause relaxation of the pelvic ligament and perhaps relaxation of the cervix during parturition. This hormone is produced by the pituitary gland and is necessary for ovulation to occur and for the development and maintenance of the corpus luteum. The only time LH is found in significant quantities is around estrus, just after the estrogen peaks which occurs at the beginning of standing heat. The LH surge causes the mature follicle to rupture and release the oocyte. Ovulation will occur from this mature follicle.