Induction and transmission of cytogenetic toxic effects of 5-fluorouracil in male germline cells of swiss mice

Cytogenetic toxicity after a single intraperitoneal exposure of three different doses (5,10 and 15 mg/kg) of 5-fluorouracil (5-FU) and its transmission in the male germline cells of Swiss mice was assessed. At 24 hrs post-treatment each of the doses of 5-FU induced statistically highly significant number of chromosomal aberrations, mostly random chromatid breaks, in the spermatogonial cells with maximum aberrations in the lowest dose. Primary spermatocytic chromosome analysis at week 4 post-treatment showed the presence of a statistically significant number of aberrant spermatocytes with atypical bivalents, mostly with autosomal and/or XY univalents. Sperm morphology assay at week 8 post-treatment exhibited higher percentages of abnormal sperm, but were not statistically significant. This indicated the gradual decline in the transmission of the induced cytogenetic toxic effects of 5-FU from spermatogonia to sperm, which might be because of gradual elimination of the grossly affected spermatogonial cells during the course of spermatogenesis.