Abstract

In order to investigate whether an alteration in experimental design would affect an apparent circadian rhythm in response of the rat testes to gonadotropins, two protocols were tested using prolactin plus LH or hCG. Time‐Variable Design: the time intervals between hypophysectomy, gonadotropin injection and autopsy were not held constant. Autopsy occurred 24 h after the morning treatment but 12 h following the evening treatment. Time‐Constant Design: all time intervals between procedures were a constant 24 h. Sex accessory tissue weights and serum testosterone were determined to assess responses. Our results show that a particular design (Time‐Variable) results in an apparent circadian response to LH and hCG when this periodicity is not actually present.