Estrogen

Estrogen is one of a group of hormones, estrone (E1), estradiol(E2),  and estriol (E3) that primarily influence the female reproductive tract, in its involvement in its development, maturation and its reproductive function. Hormones  makes up the body’s endocrine system, they are chemical messengers that function to regulate many of the normal everyday body processes we take for granted such as temperature control, (homeostasis) blood pressure control, fertility and sexual desires.

The estrous cycle comes from the Latin oestrus which means “frenzy, gadfly,” from the Greek oistros “gadfly, breeze, sting, mad impulse”, it represents the cyclic physiological changes that are induced by reproductive hormones in most mammalian females. Estrous cycles start after puberty in sexually mature females and are interrupted by pregnancies or anestrous phases which are the periods of sexual inactivity between breeding periods.

The major producers of estrogens are the ovaries and the placenta which is the temporary organ that nourishes the fetus and filters out the waste products from the baby. It is also manufactured in small quantities by the placentas of pregnant women, the liver, adrenal glands, and breasts and in males, certain cells in the testes produce low levels of estrogen. Estrogen levels in the bloodstream are at their highest during ovulation, or the egg producing period and after menstruation, when the corpus luteum or new tissue replaces the empty egg follicle.

Estrogen has an affect on the ovaries, vagina, fallopian tubes, uterus, and the mammary glands. Estrogen in the ovaries help to stimulate the pituitary gland in the brain to release the hormones that cause the follicles to develop, and later to stimulate the growth of the egg follicle. Once the egg is released, it travels through the fallopian tubes towards the uterus but whilst in the fallopian tubes the estrogen develop the thick muscular wall and for the contractions that transport both the egg and sperm cells.

In young mammals the uterus will not develop without estrogen, and once it is developed and then deprived on estrogen, it will show signs of tissue degeneration. Estrogen build and maintain a mucous membrane of the uterus, called the endometrium. They can increase the endometrium’s weight, cell number, cell types, blood flow, protein content, and enzyme activity. Estrogen also stimulate the muscles in the uterus to develop and contract; these contractions are an essential part of the removal of dead tissue during menstruation and during childbirth in the form of the placenta.

The cervix, found at the tip of the uterus, projects into the vagina, and it is thought that estrogens are responsible for the production, regulation of the flow the flow and thickness of the mucous secretions that are used to enhance sperm transport and therefore increase the chances of pregnancy. Estrogen is thought be responsible for the fact that a vagina reaches its adult size, as well as the thickening of the vaginal wall, and the increase in vaginal and the production of acidity that reduces bacterial infections in adult females.

In the breasts the actions of estrogen are complexly interrelated with those of other hormones, and their total significance is not totally understood. What is known is that they are responsible for the growth of the breasts in adolescence, the pigmentation of the nipples, and the eventual cessation of the flow of milk.

Estrogen are responsible for the structural differences between the male and female bodies. The smaller and shorter feminine bones, the broader pelvis for childbirth, and the narrower shoulders. The female body is more curved because of the fatty tissue that covers the muscles, breasts, buttocks, hips, and thighs. Other differences are in scalp hair which tends to be more permanent and therefore reduces the likelihood of a receding hairline in women, the body hair is finer and less dark. In addition, estrogen suppress the activity of the sebaceous oil-producing glands that reduce the likelihood of acne in the female.

In the male, traces of estrogen are present in the blood and urine especially during puberty and old age. Their function in the male and their interplay with the male hormones are not completely known.