mpD-1 confers extra M row formation during development. A comparison of the course of oral development between the WT (A, B, C, D, E, F, G, and H) and mpD-1 homozygotes (A′, B′, C′, D′, E′, F′, G′, and H′) grown at 39°C. White arrows mark the M rows. (A and A′) Stage 1b in the WT and 1a in mpD-1. (B and B′) Stage 2. (C and C′) Stage 3. (D and D′) Stage 4a. Note the extra M row in the mutant cell. (E and E′) Late stage 4b (WT) and early stage 5a (mutant). (F and F′) Stage 5b. There appears to be a delay in the formation of UM in the mutant cell. (G and G′) Stage 5f in the WT and 5b in the mutant cell. (H and H′) Late stage 5f. oa, mature oral apparatus; noa, new oral apparatus or OP; ma, macronucleus; mi, micronucleus.