Effect of duration of cryptorchidism on ability of mouse germ cells to regenerate and differentiate.

When 2-month-old mice were made cryptorchid for periods of up to 19 months, testicular weight fell between 0 and 10 days, remained steady until 7 months, fell rapidly until 12 months, and then remained low. The recovery of weight gain of the testes after surgical reversal of the cryptorchidism was related to the duration of cryptorchidism. After 8 months very little change in testicular weight or specific activity of lactate dehydrogenase X was obtained.