Early stage 12 egg primordia derived from αTub67C^kav-rX21/αTub67C^kav-18c females show no sign of the fast, linear motion of the non-streaming lipid droplet subpopulation that is seen in control egg primordia.

Injection of cytoplasm from embryos laid by αTub67C^kav-18c/Df(3L)55 mothers into wild-type embryos between the seventh and ninth cleavage cycle die before the larval stage. Identical injection of cytoplasm from wild-type embryos has no significant effect on survival.

Injection of cytoplasm from embryos laid by αTub67C^kav-18c/Df(3L)55 mothers into wild-type embryos between the tenth and the eleventh cleavage cycle has no effect on already established mitotic spindles and does not disturb the events of meta-, ana- or telophase. However the separation of daughter centrosomes in these embryos is slowed after injection and some spindles form abnormally or fail to form at all. In some cases, the slowed separation of daughter centrosomes leads to a failure of normal nuclear spacing and the subsequent formation of tripolar spindles due to the recruitment of a centrosome from and adjacent nucleus. In contrast, injection of cytoplasm from embryos laid by αTub67C^kav-rX21/+ mothers after the twelfth cleavage does not harm embryos.

Conditions which induce the formation of microtubules in extracts from 0-4 hour old wild-type embryos do not induce microtubule formation in equivalent extracts from αTub67C^kav-18c/Df(3L)55 embryos unless the microtubule stabiliser taxol is present.

Although eggs laid by αTub67C^kav-18c/+ females are fertilized, embryogenesis does not begin. The centrosome introduced by the sperm is duplicated and daughter centrosomes form, but these daughter centrosomes fail to move apart along the nuclear envelope and no spindle can be seen between them. Instead they remain closely associated with a tassel of microtubules with over-condensed chromosomes inside - indicative of a collapsed spindle.

Female viability and male fertility are not reduced. Some posterior structures can be identified in about 5% of embryos.

dominant female-sterile. In embryos from heterozygous females there are head lesions; some posterior structures present.