Developmental stage dependent toxicity of aminoguanidine on chick embryos.

Aminoguanidine (AG) sulfate was injected into the thin albumen of fertile eggs on the different days of incubation. The lethality of AG sulfate on the developing chick embryos became lower when the treatment was done at later developmental stage. When AG was injected on the 5th day of incubation, the frequency of retardation of development of the body and liver, aplasia of gallbladder and enlarged spleen was highest without high mortality compared with the other experiments. Embryos with liver damage could not hatch. 14C-AG hydrochloride injected on the 5th day of incubation easily distributed into the embryo through the yolk from the thin albumen of the injection site, but when injected on the 9th day, the agent transferred very little into the yolk and embryo. The change of transport in the eggs with development may elucidate the difference of lethality of AG. Additionally, it was confirmed using thin layer chromatography that a large part of the radioactivity in the embryo might be an unknown metabolite of AG and the substance was accumulated with extremely high concentration in the liver at 24-48 hr after the injection of AG on the 5th day of incubation. This is probably the main cause of the peculier abnormalities in the liver of chick embryos.