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DEVELOPMENTAL ANOMALIES DERIVED FROM EXPOSURE OF ZYGOTES AND FIRST-CLEAVAGE EMBRYOS TO MUTAGENS
Citation:
Turledge, J., W. Generoso, A. Shourbaji, K. Cain, M. Gans, AND J. Oliva. DEVELOPMENTAL ANOMALIES DERIVED FROM EXPOSURE OF ZYGOTES AND FIRST-CLEAVAGE EMBRYOS TO MUTAGENS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-93/182.
Description:
Results of continuing studies indicate that the mouse zygote and two-cell embryo stages are a window of susceptibility in the experimental induction of congenital anomalies with certain mutagenic agents. he mechanisms by which the mutagens initiate the pathogenesis of these developmental defects are not known. owever, in certain cases there is evidence that a nonconventional, perhaps epigenetic, mechanism is involved. etailed characterization of the spectrum of anomalies induced and comparison of responses at the various stages exposed allowed classification of the mutagens generally into two groups. ne group is characterized by being effective only in the early stages of zygote development and capable of producing a relatively high incidence of fetal death and hydrops. he other group affects all of the zygote stages studied as well as the two cell-embryo, but does not increase the incidence of fetal death and hydrops. xcept for hydrops, chemicals in the two groups do not differ in terms of the types of anomalies present among malformed live fetuses, which bear a resemblance to a subset of common, sporadic human developmental anomalies that are of unknown etiology. his similarity raises the possibility that certain human developmental defects may have their origins in events that happen in the zygote and early pre-implantation stages.