Phalangeal growth marks related to testis development in the frog Rana cyanophlyctis

Abstract

A study of phalangeal skeletochronology was performed to estimate the age of male frogs, Rana cyanophlyctis. Changes in testicular morphometry, kinetics of spermatogenesis and abdominal fat body mass were studied in relation to the number of growth marks in these frogs. Demineralized, stained cross- sections of distal phalanx of the 4th toe of male frogs showed growth rings that alternated with highly chromophilic lines of arrested growth (LAGs). One to five growth rings were observed in frogs with different body size; body mass (r = 0.44) and size (r = 0.47) showed poor correlation with the number of growth rings. Testicular morphometry, number of spermatogenic cysts per seminiferous tubule cross-section, and germ cells per cyst increased with the increase in the number of growth rings. Leydig cells were few in the frogs with a single growth ring and increased in second and third year but Sertoli cell number and nuclear diameter did not change drastically.