Reproductive @entity137 of 1,3-butadiene in the XXXX : cytogenetic analysis of chromosome aberrations in first-cleavage embryos and flow cytometric evaluation of spermatogonial cell killing.

@entity19 @entity137 @entity19644 @entity21430
Reproductive effects of 1,3 @entity21430 inhalation have been evaluated in male @entity19 by reduction of post-meiotic germ cells, alteration of sperm chromatin structure and transmission of chromosome aberrations to one-cell embryos. Animals were exposed for 5 consecutive days for 6 h per day to @entity21430 concentrations of 130, 500 or 1300 ppm. The testicular fraction of post-meiotic germ cells was measured by flow cytometric analysis on the basis of their DNA content. Round spermatids were discriminated from mature, elongated spermatids by their different degree of chromatin condensation. @entity21430 -induced cytotoxic effects on differentiating spermatogonia were shown by a concentration-dependent decrease of round spermatids occurring 21 days after chemical exposure, confirmed by a similar decrease of elongated spermatids measured in testes sampled 7 days later. Statistically significant effects were seen already at 130 ppm. An incomplete repopulation of the elongated spermatid compartment observed 35 days after exposure to 1300 ppm suggested that, at the highest concentration tested, @entity21430 @entity137 extended to stem cells. Alterations of sperm chromatin were revealed by its increased sensitivity to acidic denaturation in situ. The percentage of abnormal sperm was significantly increased after @entity21430 exposure of differentiating spermatogonia and spermatocytes. This suggested the induction of persistent effects interfering with chromatin remodelling during spermiogenesis. Chromosome-type structural aberrations were significantly elevated in first-cleavage embryos conceived by males mated during the first and second week after the end of exposure. The lowest effective tested concentration was 500 ppm, the same reported for dominant lethal induction under identical exposure conditions. As in the dominant lethal assay, the effect of this dose was confined to exposed sperm, while both sperm and late spermatids were affected by the inhalation of 1300 ppm. A quantitative comparison between the effects induced by intraperitoneal injections of @entity19644 or @entity21430 inhalations suggested that other reactive intermediates, in addition to @entity19644 , might contribute to mediate @entity21430 -induced reproductive @entity137 .
