Ommatidia have a variable number of photoreceptors in flies carrying N^{intraΔ.hs.2sev.F}, often four large rhabdomere cells and two or three small rhabdomere cells.

Ommatidia in which all cells carry N^{intraΔ.hs.2sev} show severely disrupted patterns of photoreceptor differentiation. Ommatidia which are mosaic for N^{intraΔ.hs.2sev} in an otherwise wild-type background can form the normal complement of 8 photoreceptors, provided that both the R1 and R6 cells do not carry N^{intraΔ.hs.2sev}. When these normally composed ommatidia are mosaic for the R3/R4 pair, the cell carrying N^{intraΔ.hs.2sev} invariably develops as the R4 photoreceptor, resulting in incorrect chirality in some cases (this phenotype is unaffected if the flies are also carrying fz¹⁵ or fz³⁷). Ommatidia in which both members of the R3/R4 pair carry N^{intraΔ.hs.2sev} can be symmetrical, although asymmetric ommatidia of the correct chiral form are also seen. The R8 cell body normally achieves an asymmetric position on the R3 rather than the R4 side of the ommatidium in wild-type flies. Frequent uncoupling of the R8 position from the R3/R4 asymmetry is seen in N^{intraΔ.hs.2sev} mosaics. In these cases, R8 cells are usually found between R5/R6, occasionally found between R1/R6 and in rare cases are found between other cells.