Veterinary Andrology and Reproductive Techniques

BIOSYNTHESIS

• Acetate → Cholesterol → Pregnenalone → Progesterone → Androstenedione → Testosterone.
• Testosterone is the major androgen produced by bull, dog and human testes. Androstenedione is the major androgen from the stallion’s testes.

In bull, testosterone is sixteen times more potent than androstenedione.

• Testosterone secreted from the Leydig cells is carried in the blood stream by an α – globulin designated as steroid binding globulin.
• 99% of the circulatory testosterone is in bound form and 1% free testosterone from circulation enters the target cell.
• In the cytoplasm of target cells, it is converted by 5- α reductase into dihydrotestosterone which is biologically active form.