gwl^Sr18/gwl¹⁸⁰ oocytes fail to maintain metaphase I.

gwl^Sr18/Df(3L)gwl^3b flies are fully viable and show no morphological defects, although females are sterile, despite exhibiting normal ovaries (and testes in the male). gwl^Sr18/Df(3L)gwl^3b females lay eggs, although these remain white. gwl^Sr18/Df(3L)gwl^3b ovaries are fully developed. Preliminary observations reveal that late (stages 13-14) eggs often have irregularly distributed yolk, in no fixed pattern. Earlier stages have uniform yolk distribution but appear to have less than same-stage controls.

In contrast to wild-type, approximately 78% of gwl^Sr18/Df(3L)gwl^3b oocytes have widely scattered chromosomes, with the number of chromosome masses varying from two to twelve. Multiple chromatin masses might be caused by reduced meiotic exchange, or precocious loss of sister-chromatid cohesion, or broken chromosomes resulting possibly from faulty meiotic exchange. A few of the meiotic spindles are aberrantly shaped, but all of the multipolar spindles contain multiple DNA masses. These abnormal spindles probably reflect nucleation of individual 'mini-spindles' from the multiple chromosome masses.

gwl^Sr18 flies show no significant mitotic defects.

In gwl^Sr18/Df(3L)gwl^3b oocytes, three or four centromeric foci are observed, indicating the presence of separated sister chromatids. This is observed in 94% of mutant oocytes with more than six DNA masses (31% with three foci and 63% with four foci), while only 6% show one or two foci. More than four foci were never observed.