Homozygous females have a grandchildless phenotype with a penetrance of 95% at 25^oC.

Embryos derived from homozygous females show reduced nuclear migration throughout the cleavage stages, with no posterior migration detected at cycle 2. The orientation of the two sister nuclei with respect to the antero-posterior axis at this stage is random, in contrast to wild-type.

Embryos derived from homozygous gs(1)N26¹ females raised at the restrictive temperature (25^oC) had hardly any space under the vitelline membrane at the posterior pole throughout the cleavage stage. Nuclear arrival in the posterior pole periplasm at the cleavage stage is delayed by 30 minutes compared with nuclear arrival in other regions. This is due to delayed migration of the nuclei. F-actin organisation is abnormal at the cleavage stage. gs(1)N26¹/Y male flies show a low lethality at the pupal stage.

More than 95% of eggs derived from homozygous females maintained at 25^oC have a larger number of nuclei in the anterior region and a smaller number of nuclei in the posterior region than normal. More than 80% of eggs derived from homozygous females maintained at 18^oC have a normal pattern of nuclear division and migration. 95.7 +/- 3.4% of the offspring of homozygous females raised at 25^oC are agametic. 35.9 +/- 14.3% of the offspring of homozygous females raised at 18^oC are agametic. The penetrance of the phenotype is not affected by the age of the females. The temperature-sensitive period is in the pre-vitellogenic and germarium stages of oogenesis.

Fecundity and fertility of homozygous females low; mortality of sons higher than that of daughters. Fraction of surviving progeny agametic depends on temperature of oogenesis; 93% agametic at 25^oC, 56% agametic at 18^oC. In eggs produced at 25^oC migration of nuclei to posterior pole abnormal; almost no pole cells produced in half the embryos. Polar granules present in posterior egg cytoplasm, defects in failure of nuclear migration.