Abstract
Summary
Inhibitory and teratogenic effects of various doses of benzimidazole homologues, 2,5-dimethyl- (DMB), 2-ethyl-5-methyl- (EMB), and 2-hepta-5-methyl-(HMB), were studied in the chick embryo following injection into the albumen prior to incubation. Three criteria of determining embryonic response were employed: lethality. inhibition curves derived from cumulative % embryos which ceased development at progressive stages, and types and incidence of types of malformations. EMB and HMB had about the same degree of lethality and were considerably more lethal than DMB. Inhibition curves from equivalent doses were different for each compound, and dose increase caused a different pattern of change in inhibition curves; thus, the embryo responds specifically to equivalent doses of each compound. Certain types of malformations resulted from all inhibitors, others resulted from only DMB and EMB, others from EMB and HMB, and still others from only EMB. The incidence of each different type of malformation was reflected in inhibition curves since most types of malformations were associated with embryos of a limited embryonic age period. Although there were differences in response to the compounds, there were also similarities.
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