X-chromosomal nondisjunction induced by aging oocytes of Drosophila melanogaster: the special susceptibility of mature eggs.

In Drosophila melanogaster suppression of oviposition results in an aging of both mature and immature oocytes. When oviposition was suppressed for four days, the incidence of X-chromosomal nondisjunction (XXY exceptions) in mature oocytes was more than doubled, whereas in immature oocytes the nondisjunction frequency was not increased. It is shown that this special susceptibility of mature oocytes to aging-induced nondisjunction has to be considered in experiments on the induction of nondisjunction by chemical agents.