The Development of Normal and Homozygous Brachy (T/T) Mouse Embryos in the Extraembryonic Coelom of the Chick

Abstract

From crosses of brachy short-tailed mice (T/ + ) inter se, 149 embryos (7 days after copulation) were transplanted to the extra-embryonic coelom of the chick. 84 were successful, the embryo being alive when removed after 18 to 47 hrs. Of 81 embryos, 28 were normal; 27 showed various degrees of abnormalities, with reduced developmental potencies, possibly representing the T/+ embryos; and 19 showed characteristic abnormalities with tuberous allantois, which fits very well the expectation of 1/4 being T/T. T/T embryos will thus develop true to their genotype, even if explanted before the time at which morphological differences appear. The possible causal role of the allantois in the development of these embryos is discussed.