Major Malformations in Trout Embryos Irradiated Prior to Active Organogenesis

Abstract

Frequencies of major malformations of the eyes and the bodies of trout embryos were studied following exposures of embryos to 10, 100, and 1000 rads of x-rays at early cleavage, late cleavage, blastula, and germ ring stages. A sham-irradiated control was carried out for each stage of irradiation. Contrary to evidence from mammalian studies, embryos of trout developed a high incidence of major malformations when irradiated prior to active organogenesis, there being a peak effect of 40% eye malformations and 35% body malformations at late cleavage. The apparent lack of quantitatively similar responses in mammals must be due to loss of potentially malformed individuals to study through selective failures to implant or through postimplantation deaths. A curious finding was that the various kinds of malformations were apparently identical to those previously observed as a consequence of irradiations of sperm and eggs. Thus, the same vulnerable processes must be upset in similar ways both by exposures of the em...