Observations on a set of radiation-induced dominant<i>T</i>-like mutations in the mouse

Abstract

SUMMARY Genetic analysis of seven dominant short tailed mutations independently induced by radiation of male mice showed that six were allelic to T (Brachyury) but not identical to it. Homozygotes for each mutant die at least 2 days earlier than T / T homozygotes; two that were studied histologically are indistinguishable from one another. The development of these abnormal embryos is arrested by seven days of gestation, when cells of embryonic ectoderm cease proliferation and become pycnotic. Endoderm and extra-embryonic ectoderm do not seem to be primarily affected, and survive and grow for at least 2 days more. Serological studies of one of these mutations suggest that it is a deletion. A review is presented of these and other T -like mutations that have been described; from this it appears that five different categories of T -like mutants are discernible.