hypomorphic allele - genetic evidence
gap phenotype | embryonic stage | recessive
lethal - all die during embryonic stage | recessive
some die during embryonic stage | recessive
cephalopharyngeal skeleton
embryonic mesothoracic segment
embryonic metathoracic segment
embryonic prothoracic segment
Thoracic segments 2 and 3 are absent and the cephalopharyngeal skeleton is poorly formed.
Bender.
Revertant.