RESUMEN
A comparative study on the cytotoxic potential of anticancer-antibiotic mitomycin C has been made on tumour-bearing and normal mice considering precocious desynapsis of sex bivalent as parameter. The study indicates a strikingly differential effect of the drug on the phenomenon in two different types of mice. The administration of mitomycin C at therapeutic dose although enhances the frequency of precocious desynapsis of XY-bivalent in non-tumour (normal) mice to a significant extent (compared to control), the same drug at the same dose fails to produce a similar effect on tumour-bearing specimens. Discussions have been made on: (i) the probable cause for this differential effect, (ii) the mechanism of mitomycin action on precocious desynapsis of sex bivalent and, (iii) the possible significance of the findings in relation to cancer chemotherapy.