CYTOGENETIC EFFECT OF CHEMOSTERILANTS IN HOUSE FLY SPERM: INCIDENCE OF POLYSPERMY AND EXPRESSION OF DOMINANT LETHAL MUTATIONS IN EARLY CLEAVAGE DIVISIONS

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Abstract
The treatment of male house fles with sterilizing doses of tepa, hempa, or several intermediate analogs before mating with untreated females did not greatly reduce the number of eggs that were fertilized. However, in comparison with the controls the number of sperm entering the egg was significantly different in eggs fertilized with sperm from males treated with tepa, hempa, and three analogs. Because of the normal occurrence of polyspermy, the possible inactivation of sperm by the chemosterilants would not be as evident in a polyspermic insect as in a monospermic species.The cytological examination of the embryonic chromosome abnormalities produced by the chemicals revealed that all test chemicals resulted in the formation of chromosome bridges and fragments during early embryogenesis. These genetic abnormalities led to other developmental abnormalities and caused cessation of embryonic development. Although the chemicals differ structurally, all eventually produced similar cytogenetic damage, but there was evidence of some variation in the time of expression and distribution of the various kinds of cytogenetic aberrations produced by the various chemicals.