The reproductive system in males include the testis and the epidydimis and the prostate gland. In females the reproductive system is comprised of the vagina and the uterus and the ovaries.
Testosterone is a male sex hormone that stimulates the generation of the male sexual secondary characteristics and in addition it stimulates the descending of the testes in the fetus. It is secreted by the testis. The cells in the testis that secrete testosterone are called leydig cells. Testosterone synthesis is in turn stimulated by a hormone that is called luteinizing hormone. This hormone is secreted by the anterior pituitary gland. It stimulates the leydig cells to produce testosterone.
The testis secretes other male sex hormones than testosterone such as di-hydro-testosterone.
Testosterone is also important for blood cells formation. Testosterone stimulates red blood cells formation indirectly by stimulating erythropoietin synthesis. Erythropoietin stimulates red blood cells synthesis. Its synthesis occurs normally in the kidney.
Another hormone that is also secreted by the anterior pituitary gland is called follicle stimulating hormone. This hormone functions by stimulating spermatogenesis. It does so by converting spermatids into sperm. In addition this hormone is secreted also in the female and has a different function that is related to the maturation of the follicles of the ovaries.
Estrogens are also important hormones for sperm production. They are synthesized from testosterone in the sertoli cells.
The prostate gland is situated around the male urethra. It secretes a basic fluid which contains ions in addition to the important enzyme acid phosphatase which is used as a marker for prostate cancer. its elevated levels can be indicative of prostate cancer. Another compound that the prostate gland secretes is called prostate specific antigen. This compound is also a marker for prostate cancer.
Other cells in the body that secrete male sex hormones are located in the adrenal gland. The adrenal gland secretes several hormones ( androgens).
Tumors of the adrenal gland are particularly important in females where masculinizing properties appear on women such as hair growth and other clinical symptoms such as restoration of the menses after its cessation.
The ovaries in females secrete two important hormones. These are estrogens and progestins. The most important estrogen is estradiol and the most important progestin is progesterone. Estrogens are responsible for stimulating secondary sex characteristics in females. Progesterone and other progestins are responsible for preparing the uterus for pregnancy and for breast lactation.
Estrogen and progesterone are secreted extensively by the corpus luteum after ovulation has occured. These two hormones exert an inhibitory effect on the pituitary gland so that it does not secrete the hormones follicle stimulating hormone and luteinizing hormone. Estrogen and pregesterone have extensively secreted during pregnancy by the placenta of the mother.