Fig. 1. Telomerase activity is induced by Kitl in mitotic spermatogonia. (A) Spermatogonial cell extracts were obtained from cells that were freshly collected (T0) or after 24 hour in culture without (control; 24 hr) or with the addition of Kitl. Enzyme activity was assessed by the TRAP assay in the presence (+) or absence (-) of RNase A. (B) Spermatogonial cell extracts were cultured for 24 hours (24h) in the absence of Kitl and then for further 24 hours in culture without (48h- Kitl) or with the addition of Kitl (48h+ Kitl). Enzyme activity was assessed by the TRAP assay in the presence (+) or absence (-) of RNase A.