In human males, testosterone is mainly produced by

(A) Leydig cells # Testosterone, the principal hormone of the testes, is a C19 steroid with an -OH group in the 17 position.> It is synthesized from cholesterol in the Leydig cells & is also formed from androstenedione secreted by the adrenal cortex> The testes are made up of loops of convoluted seminiferous tubules, in the walls of which the spermatozoa are formed from the primitive germ cells (spermatogenesis). Both ends of each loop drain into a network of ducts in the head of the epididymis. From there, spermatozoa pass through the tail of the epididymis into the vas deferens. They enter through the ejaculatory ducts into the urethra in the body of the prostate at the time of ejaculation. Between the tubules in the testes are nests of cells containing lipid granules, the interstitial cells of Leydig , which secrete testosterone into the bloodstream. The spermatic arteries to the testes are tortuous, and blood in them runs parallel but in the opposite direction to blood in the pampiniform plexus of spermatic veins. This anatomic arrangement may permit countercurrent exchange of heat and testosterone.> Leydig cells secrete testosterone in response to LH