ABSTRACT
Some of the earliest experiments to investigate the function of the testes were conducted by Berthold in the mid-nineteenth century. He conducted experiments with roosters and showed that transplantation of testes into castrated roosters (capons) led to regression of the changes that occurred as a result of castration, namely the regrowth of comb and wattles and changes in behaviour. Berthold concluded that a secretion from the transplanted testis was responsible for these changes. Berthold’s experiments were repeated by different scientists with variable success. Eventually, Berthold’s conclusions were verified, as a result of work by McGee (1927) and Gallagher and Koch (1934). Both of these groups conducted modified versions of the Berthold experiment, in which they used an alcohol extract of bull testicle to stimulate the regrowth of the combs of castrated roosters. Following research that proved extracts from men’s urine had a similar stimulatory effect upon regrowth of the comb of castrated roosters (Ruzicka et al., 1934), it became accepted that the testes produced an active extract responsible for the development and maintenance of male characteristics (Kochakian, 1993b).
