Time dependent glucocorticoid exposure in the neonatal period (21 days) and adult plasticity in terms of testes growth and function and neuro-endocrino axes have been studied in Charles foster rats. Adult hormonal profile and germ cell kinetics by histometric enumeration were evaluated. The results clearly suggest that, neonatal hypercorticolism induces adult plasticity in terms of advanced puberty onset, early onset of spermatogenesis and permanently hyporegulates neuro endocrine adrenal axis and up regulates thyroid axis. The hypothalamo-hypophysealgonadal axis also seems to be down regulated. The overall germ cell number is increased though Sertoli cell number is reduced, suggesting reduced apoptosis and increased number of germ cells being supported by Sertoli cells. Time dependent effect of corticosterone is seen in the form of relatively higher loss of advanced germ cells and decreased tubular length, basement area and Sertoli cell number in morning Cort treated rats. It is hypothesized from the present observations that, neonatal Cort excess can decrease germ cell apoptosis by genetic programming of Sertoli cell secretion and other functions.