Heterozygous and hemizygous females are sterile at 18^oC. Approximately 10% of eggs derived from these females show a phenotype similar to αTub67C^Tom-4091 and αTub67C^Tom-16d, in the remaining 90%, embryogenesis proceeds to stages 13 to 17, but is not completed. At 29^oC, approximately 20% of eggs derived from heterozygous or hemizygous females hatch, and a significant fraction of the larvae develop to adulthood. At 29^oC, embryogenesis proceeds to stages 13 to 17 but is not completed in 70% of eggs derived from heterozygous females. Embryos in which embryogenesis proceeds to stages 13 to 17 but is not completed show normal cleavage divisions, blastoderm formation and gastrulation. The central nervous system and peripheral nervous system are highly disorganised in these embryos. The brain remains rudimentary, and the commissural and longitudinal processes of the ventral nerve cord are disrupted. The sensory neurons and their axons are abnormally oriented.

Female viability and male fertility are not reduced. The female and male pronuclei approach each other and almost fuse, however they do not divide.

Eggs of heterozygotes: sperm pronuclei may or may not divide but no fusion or further development.