Testosterone:

Source of secretion:

It is secreted in large quantities by the testes and in small quantities by the adrenal cortex. They are also known as androgens. In the testes it is secreted by leydig cells.

Chemistry:

Testosterone is steroid hormone synthesized from cholesterol and has 19 carbons. So it is called as C19 steroid hormone.

Metabolic roles:

A. During fetal life:

a. Sex differentiation in fetus:

• In fetus there are two genital duct ie. Mullerian duct and Wolffian duct. Mullerian duct give rise to femal accessory sex organs and Wolffian duct give rise to male accessory sex organs. So if testosterone is secreted from the genital ridge of fetus during intrauterine life then wolffian duct give rise to male sex organ otherwise femal sex organs are appeared.

b. Descent of testes:

• Initially, testes are developed in the abdominal cavity and pushed into scrotum. Testosterone is needed for this.

B. During adult life:

a. Effect on sex organs:

• Testosterone helps in increasing the size of penis, scortum and testes.

b. Effect on secondary sexual character:

• Testosterone helps in increasing muscular growth and increases the thickness of skin.