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Origins of Testosterone Replacement

In one of the first endocrine experiments ever recorded, Professor Arnold A. Berthold (1803-1861) of Gottingen did a series of tests on roosters in 1849 while he was curator of the local zoo. Bethold found that a rooster's comb is an androgen-dependent structure. Following castration, the comb atrophies, aggressive male behavior disappears, and interest in the hens is lost.

Importantly, Berthold also found that these castration-induced changes could be reversed by administration of a crude testicular extract (or prevented by transplantation of the testes). Berthold concluded:

"The testes acts upon the blood,
and the blood acts upon the whole organism."

SYNOPSIS OF ROOSTER EXPERIMENTS OF
A. A. BERTHOLD (1849)

  1. Castrate roosters ---->
    • Small comb and wattles
    • No interest in hens
    • No aggression towards other males
  2. Remove testes and replace ---->
    • Normal comb and wattles
    • Normal male behavior
  3. Transplant testes ---->
    • Normal comb and wattles
    • Normal male behavior
Berthold, A.: Transplantation der Hoden. Arch Anat Physiol Wissensch, 42, 1849.

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