A Note on Abnormalities induced in Mouse Embryos by Trypan Blue

In 1948 Gillman, Gilbert, Gillman & Spence reported the results of experiments in which rats which had been injected at fortnightly intervals with 1 c.c. of 1 per cent, trypan blue were allowed to produce offspring. A most remarkable variety of anatomical abnormalities, often of a very severe character, was found in the young. The malformations included hydrocephalus, spina bifida, eye and tail defects, and alterations in internal organs. Some of the defects were similar to abnormalities which can be produced by mutant genes, either in the rat or in other mammals, and could therefore be regarded as belonging to the illdefined class of ‘phenocopies’. Since the mammal embryo is notoriously difficult of access, and comparatively little is known of its developmental physiology, the phenomena discovered by the South African authors seemed worthy of further investigation.