Re. Sotomayor et al., A PROCEDURE TO STUDY UNSCHEDULED DNA-SYNTHESIS IN RAT SPERMATOGENIC CELLS IN-VIVO - STRAIN DIFFERENCES BETWEEN FISHER-344 AND SPRAGUE-DAWLEY RATS, Toxicology letters, 89(1), 1996, pp. 77-81
A liquid scintillation counting (LSC) procedure was used to study unsc
heduled DNA synthesis (UDS) in pachytene spermatocytes and spermatids
from Fisher-344 (F344) and Sprague-Dawley (SPD) rats treated with meth
yl methanesulfonate (MMS). MMS induced a large, dose-dependent, UDS re
sponse in pachytene spermatocytes from both rat strains. On average, F
344 pachytene spermatocytes showed a larger UDS response than those of
SPD rats. The lowest dose of MMS that elicited a significant UDS resp
onse was 1 mg/kg in F344 rats but 5 mg/kg in SPD rats. Early spermatid
stages from F344 rats also showed a larger UDS response than those fr
om SPD rats. The time interval at which spermatid stages showed the ma
ximum UDS response was between 20 and 24 days after MMS treatment. It
is concluded that UDS can be measured quantitatively in rat spermatoge
nic cells in vivo by using the LSC procedure.