Is Testicular Function in Immature Rats Increased Rather Than Decreased by a Moderate Increase in Temperature?

Abstract

Spermatogenesis cannot be maintained at normal body temperature, but the cellular mechanisms responsible are unknown. The most common experimental approach to study this is to examine the effects of experimental cryptorchidism or heat application in adult animals. Experimental cryptorchidism is generally obtained by returning a mature descended testis back into the abdomen. This approach has been used in a great number of studies and the general conclusion is that it results in a rapid degeneration of early spermatids and spermatocytes (van Demark and Free, 1970; Setchell, 1978). It has been suggested that these particular cell types are directly sensitive to increased temperature in vitro, possibly by effects on their cell membranes (Lee and Fritz, 1973) or on their protein synthesis (Nakamura et al., 1978). When experimental cryptorchidism is induced in newborn pigs, it eventually results in decreases in testis weight, number of gonocytes and in total Leydig cell mass (identical changes as in congenital cryptorchid pigs; van Straaten, 1978), suggesting that cell types other than developed germ cells are sensitive to increased temperature.