Stage 15 hhunspecified embryos have only ~13 genital disc precursor cells, instead of the wild-type number of 22.
Some mild defects in germ cell migration are seen in hhunspecified/+ embryos: fewer than 20% of the stage 13 to 16 embryos have four or more mispositioned germ cells(n=25).
hhMrt/+ embryos have defects in germ cell migration: and about 60% of the stage 13 to 16 embryos have four or more mispositioned germ cells (n=25). These defects are more severe in hhMrt/hhunspecified embryos: >90% of stage 13 to 16 have ten or more mispositioned germ cells (n = 20).
Mutants show dramatic increase in the number of midline glial cells. By the end of embryogenesis most of the midline glial cells are missing. Midline neurons are reduced in number. Commissure formation is delayed. In stage 13 only a few commissural axons have crossed the midline. In stage 16 embryos, commissures have formed but are reduced in size.
Formation of the visceral mesoderm is normal in homozygous embryos, and the visceral mesoderm migrates to cover the gut and form midgut constrictions.
Embryos show a germ cell migration defect and a significant reduction in the number of gonadal mesodermal cells.
The posterior naked section of the ventral part of each segment is deleted in hhunspecified mutant embryos and is replaced by a mirror image duplication of the anterior denticle belts. Segment boundaries appear to be missing.