run3 embryos display cephalic furrow initiation events of "type III+", in which three or more cells undergo shortening simultaneously, and an increase in the number of initiating cells per area unit. But cephalic furrow formation is abrogated.
run3 mutant embryos lack the second midgut constriction and only form first and third constrictions.
Cell intercalation is reduced by more than 30% in run3 mutant embryos, accompanied by slower edge contraction.
Anterior-posterior polarization of cells in the extending germband is partially disrupted in run3 hemizygous embryos.
In run3 null homozygotes the presumptive anal plate is well formed.
Hemizygous run3 embryos that are homozygous for runt14.5 have nearly wild-type segmentation.
Initially the parasegments have variable development. Later the ftz stripes become limited and a variable pattern of eve stripes survives with irregular boundaries.