midB23/mid2 mutant embryos exhibit gonad development defects that are similar in penetrance and severity to midB23 homozygotes.
An additional, ectopic eve-postive neuron is observed within the nerve cord in 29-30% of hemisegments in ~14 hour-old mutant embryos. In midlos1/mid2 embryos, the ectopic neuron is seen in 24-25% of hemisegments; in mid2/mid1 embryos, the ectopic neuron is seen in 33-34% of hemisegments; in mid2/Df(2L)Exel6012 embryos, the ectopic neuron is seen in 50-56% of hemisegments. Further experiments suggest this is an ectopic RP2 (eRP2) neuron, resulting from the transformation of a wild type neuron termed the 'M-neuron', with an ectopic GMC-1-like cell and a RP2 sib-like cell also present. This extra RP2/sib lineage is formed 2-2.5 hours after the development of the bona fide RP2 lineage.
Mutant embryos show motorneuron projection defects.
Stage 16 mid2/Df(2L)cl-h2 embryos have a relatively normal number of cells in the dorsal vessel, but they have increased numbers of elongated, putative ostia forming cells per hemisegment in the heart region and a corresponding decrease in the number of cells expressing cardioblast markers.