Male sex hormones are also collectively known as androgens. Testosterone is the main androgen with dihydrotestosterone comprising an additional androgen. Testosterone is mainly secreted by the testes, although the adrenal cortex also secretes a little of this male sex hormone. In certain tissues, testosterone is chemically transformed into dihydrotestosterone in order to provide an effect in the body.
Testosterone is produced in response to tropic hormones. The hypothalamus releases GnRH, which in turn stimulates the anterior pituitary for the release of LH and FSH which are collectively known as “gonadotropins”. LH triggers the secretion of testosterone, and then together with FSH, they promote spermatogenesis.
Testosterone secretion throughout life cycle
The secretion of testosterone is not a continuous process throughout the entire life of males as it occurs only after puberty. Prenatal testosterone secretion is what determines the sex of the fetus. Shortly after birth, the secretion of testosterone is just about stopped. Thereafter, during puberty, the secretion of testosterone resumes and will be maintained for the rest of the man’s life.
During the life of the adult male, the secretion of testosterone is consistently maintained. Therefore, testosterone is secreted in the male’s body only to:
• Determine the child’s sex (and properly form the male reproductive organs)
• Enable reproductive function.
On the basis of these 2 functions, any problem with the levels of testosterone in the body would either prevent the development of appropriate reproductive organs or cause the lack of fertility. The development of the primary and secondary sex characteristics are as a result of the specific effects of testosterone which enable reproductive function during puberty and from then on.