abs^14B/Df(3R)231-5 embryos at the restrictive temperature display severe defects in neuroblast polarity. Mitotic spindles occasionally fail to orient along the apical-basal axis. Approximately 32% of hemisegments have a duplicated eve cell at the RP2 position. Mutant embryos subjected to a 45 min pulse at the restrictive temperature show duplications of the eve positive DA1 muscle in 34% of the hemisegments.

When mutant embryos are shifted to the restrictive temperature at any point from egg laying up to approximately 3 hours, they develop normally up to gastrulation. At later stages of development abs^14B embryos show defects within 30 minutes of a shift to 32^oC. Serious morphological effects are seen during gastrulation. The ventral cells of the blastoderm are unable to carry out their normal cell-shape changes. Only a shallow furrow forms and no mesodermal cell layer is formed. No delamination of neuroblasts occur and the epithelial cells become tall and thin. If embryos are shifted to the restrictive temperature after neuroblasts have segregated. the neuroblasts continue to develop. However, neurite outgrowth appears to be randomised, with a preference for growth towards the exterior of the embryo (unlike the wild-type where they extend towards the posterior and interior). If embryos are shifted to the restrictive temperature after gastrulation, the pole cells that pass through the midgut epithelium disperse widely within the embryo. In mutants shifted before gastrulation, the pole cells are not internalised and they distribute over the surface of the embryo. Also, head involution often does not occur regularly. Synchrony of mitosis and normal spindle orientation are disrupted in the developing embryo. If adults are shifted to the restrictive temperature during pupation they fail to eclose. If female adults are moved to the restrictive temperature immediately after eclosion, even after two days, the ovaries of these females contain no mature eggs. In most cases the egg chambers do not develop beyond stage 9. Frequently the nucleus in mutant oocytes do not reach the anterior dorsal position within the oocyte. In nurse cells and follicle cells apoptosis occurs prematurely.