ABSTRACT
As a result of the suggestion by Crew (1922), verified by Fukui (1923 a, b, c) and also independently by Moore and his associates (Moore, 1924 a, b; Moore & Chase, 1923; Moore & Oslund, 1924), the scrotum is now known to act essentially as a thermoregulator, the duty of which is to maintain a physiologically optimum temperature for testis function. Moore & Quick (1924) have shown that the temperature of the scrotum in various laboratory rodents is from 1 to 7° C. below peritoneal temperatures; and Fukui, and Moore and his collaborators, as quoted above, have shown conclusively that the mammalian testes do, in fact, require to be maintained at temperatures lower than those of the body in order to carry to completion their function of germ cell differentiation. If the temperature of the scrotum is experimentally raised to that of the body, the germinal epithelium shows rapid, and eventually complete, degeneration and the resulting atrophic testes consist of connective and interstitial tissue with very little but Sertoli cells discernible within the tubules. The sensitivity of germinal tissue to heat is extended to the mature spermatozoon since Heller (1929) found that sperm in the scrotal epididymis will live for 65 days, whereas this period is reduced to 14 days when the epididymis is elevated into the abdomen. Further, the very short life of mammalian sperm in the reproductive tract of the female, usually a matter of hours (for review see Hartmann, 1932), is presumably due also to the destructive action of heat.
