A minute deficiency in linkage group II of the mouse, involving the short-ear locus and at least one other functional unit, was found to be lethal by day 8 after coitus when homozygous. The earliest time at which mutants could be detected was 7 days 16 h after coitus. Histologically, the mutant embryos showed overgrowth of ectoderm and trophoblastic giant cells. The mesoderm was almost entirely lacking and the mutant embryos were smaller than their normal litter-mates.

It was concluded that the mutant was first expressed morphologically late on day 7 after coitus and that its primary effect was to stimulate growth of extra-embryonic ectoderm.

Copyright © 1972 by Company of Biologists
1972
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