Eggs laid by homozygous mutant mothers exhibit three classes of phenotype. Pronuclear arrest embryos exhibit pronuclear arrest at the end of meiosis. Type II embryos escape pronuclear arrest and undergo a few rounds of nuclear division before arresting. Type I embryos degenerate from pronuclear or Type II arrests.

Females doubly mutant for gnu³⁰⁵ and fs(1)Ya⁵ or fs(1)Ya^14-77 exhibit gnu-like or fs(1)Ya-like nuclear morphology.

Mutant embryos arrest either with multiple abnormal nuclei or at the pronuclear stage, with fewer than four abnormally condensed nuclei, presumably derived from the sperm and female meiotic products. 67% of embryos are pronuclear arrested, 33% have multiple abnormal nuclei. Type II embryos of the multiple nuclear arrested class show fewer than 16 nuclei, which are not fragmented. These embryos never develop to the blastoderm stage.

Weak allele. Most embryos from females homozygous for fs(1)Ya^14-77 arrest at multinuclear stages rather than at the pronuclear fusion stage (in contrast to the strong fs(1)Ya² allele). More than 10% of these multinuclear embryos arrest as gastrulae.

Eggs are laid.

Homozygous females lay eggs that fail to hatch.