Hormones in Reproduction
This hormone is only found in female body. Progesterone is the second hormone produced by the ovary (in early stage of menstrual cycle) and corpus luteum (latter stage of menstrual cycle). During pregnancy, progesterone is produced by the placenta. Organs stimulated by progesterone are the uterus and the female breasts. The actions of this hormone are the following:
- Prepares the endometrium for possible embryo implantation by stimulating the secretion of endometrial glands causing the endometrial vessels to become dilated and tortuous.
- During pregnancy progesterone:
- Nourishes the implanted embryo by inducing cell growth of the fallopian tubes and uterine lining.
- Decreases uterine contractions.
- Prepares breast for lactation, however, it inhibits prolactin secretion.
Prolactin is produced in the posterior pituitary gland (PPG) which is responsible for stimulating the female breasts during lactation. The main function of this hormone is:
- Stimulates lactinogenesis. (Lactinogenesis is the production and secretion of milk.) Estrogen and progesterone produced by the placenta during pregnancy inhibits effects of active milk production until after placenta is expelled at birth. Prolactin secretion is stimulated by the sucking of a newborn to maintain milk production.
Oxytocin like Prolactin is produced by the posterior pituitary gland. This hormone stimulates the female breast and the uterus to contract during and after birth. The presence of this hormone is very important as it does the following:
- Helps expel the fetus out of the uterus during delivery. Uterine contractions brought about by the presence of oxytocin causes the expulsion of the baby during delivery.
- Controls bleeding after delivery. Oxytocin stimulates postpartum contractions that compress the uterine vessels thereby controlling bleeding.
- During breastfeeding, let-down or milk-ejection reflex is stimulated with the presence of oxytocin.
Testosterone in males is produced by the testes. In females the adrenal glands and ovaries produce small quantities of this hormone. In women, small amount of androgenic (masculinizing) hormones from the adrenal glands cause growth of pubic and axillary hair at puberty. Most androgens such as testosterone are converted to estrogen in females. The following functions of testosterone are noted in males:
- Stimulates the development of the male sex organs in fetus.
- Induces the growth and division of cells that mature sperms.
- Promotes the development of secondary male sex characteristics.