Strong allele. The bristles (macrochaetae and microchaetae) of the adult notum and abdomen of frtz³³ hemizygotes have an altered orientation and usually point towards the midline (in wild-type flies these bristles point posteriorly). Cell hair polarity and number are altered in the wing, with the cell hair polarity phenotype being stronger at 18^oC than 29^oC. At 18^oC, substantial regions of reversed (proximal pointing) hair polarity are seen, especially on the ventral wing surface. Most cells showing reversed wing hair polarity have wild-type hair number, although a high proportion of cells produce two or more cell hairs in the mutant wing. Small homozygous clones in the wing can display hair polarity phenotypes, but no substantive changes in polarity are seen outside of the clone. Cells at the edges within a homozygous clone often produce additional wing hairs, whereas cells surrounding the clone never do. This indicates that the wing hair phenotype is cell autonomous. The change of cell hair polarity seen in the clones is similar to that at the same position of a homozygous wing. Homozygous first instar larvae show abnormal patterning of ventral denticles; both the spacing and the alignment of denticles within the denticle rows is disrupted, especially in the three anterior rows of the denticle belts. The mutant denticles still point anteriorly or posteriorly, as in wild type. Individual denticles often appear smaller than normal.