Changes in testicular allometric growth curves.

Objective criteria are needed for defining, in various animal species, changes occurring at puberty. Particularly required are estimates of the relationship of alterations in the growth of the whole body to the sex organs and the secondary sexual characteristics. A procedure that has been widely employed has been to plot testicular weight as a function of time and to observe inflection points.' The difficulties with this method are twofold. First, the exact age of the animal may not be known (especially when wild species are studied). Second, a change in the rate of organ growth with time (d(organ weight)/dt # constant) might reflect the result of transient underor overnutrition, or other factors, and not a pubertal alteration. For these reasons, it appears of value to attempt to relate organ sizes to body weight and to detect any changes that mark the time of puberty. Since puberty is characterized by gonadal maturation, and in some species by a change in bone growth, the gonads and bones would appear to be key organs in such an investigation. In the present communication we examine the relationship of testicular weight to body weight in several species.