Heterozygous gw¹/+ parents produce embryos with disorganised internal structures 90-130 minutes after egg deposition. These embryos are homozygous gw¹, whereas those embryos that develop normally are found to have at least one wild-type gw allele. Homozygous gw¹ mutant embryos fail to cellularise and form DNA-gw-membrane aggregates.

Homozygous gw¹ embryos exhibit defects in nuclear spacing and morphology beginning at approximately nuclear cycle 10, as they migrate to the embryo cortex. Mutant embryos exhibit fewer cortical nuclei, with irregular spacing. These nuclei exhibit abnormally positioned centrosomes. Two hours after egg deposition gw¹ mutant embryos show larger than normal nuclei and an abnormal clearing of the embryo cortex. By 3 hours after egg deposition, no recognizable nuclei are found, and large multivesicular bodies and homogeneous patches devoid of organelles are present. These are composed of filamentous elements, which may represent large tubulin aggregates.

Homozygous gw¹ mutant embryos are extremely fragile as a result of what appears to be abnormal cellularisation.