Seasonal variation in testicular and fat-body weight and plasma testosterone and androstenedione concentration in the lizard <i>Cordylus polyzonus</i> (Sauria: Cordylidae)

Abstract

Seasonal variation in testicular and fat-body weight and plasma testosterone and androstenedione concentration of the lizard Cordylus polyzonus is described. Testicular recrudescence commenced in autumn (April), reaching a peak in early spring (September) and regression followed during mid-spring to early autumn (October-March). The onset of testicular recrudescence coincided with decreasing ambient temperature and photoperiod and increasing rainfall. Fat-body weight was small during most of the testicular recrudescence phase, with an increase commencing in spring (September). A peak in fat-body weight was reached during late spring - midsummer (October-December) and followed by a progressive decline to baseline values in winter. Plasma testosterone and androstenedione concentrations followed a bimodal annual pattern, a first peak occurring in late summer/early autumn (February/March) and the second in spring (September/October).The first peak coincided with the onset of testicular recrudescence and the second with maximum testicular weight.