The pharynx, otic vesicles, hindbrain, notochord, and gill are apparently normal. The gene appears to be a simple recessive, but penetrance is incomplete and variable. Rearing the embryos at 10 degrees C increases penetrance. Typically homozygotes exhibiting the phenotype are unable to eat and die soon after hatching. Larvae homozygous for this mutation become recognizable after they have been eating for a week or more.
Short toes is a recessive lethal mutation involving the kidneys, the Mullerian ducts and the limbs.
Mutant animals can be readily identified by their short limbs and, especially, the reduced number of phalanges once front limb development is complete. Ascites, due to the incomplete development of the Mullerian ducts, becomes apparent only in the older juvenile. Homozygotes die of renal failure at about one year. Click on the images below for a larger picture. No carriers of this mutation are identified in the colony today.