Non-disjunction of the Sex-chromosomes in the Male of Drosophila melanogaster

Abstract

THE discovery that certain human abnormalities have a chromosomal basis has stimulated renewed interest in the phenomenon of non-disjunction. Theoretically, non-disjunction may occur in both the male and female germ cells at either the first or second meiotic division and may give rise to a considerable variety of non-disjunctional types in the progeny. In practice, only non-disjunction occurring at the first meiotic division in oocytes has so far been studied in Drosophila. The present communication reports the occurrence of spontaneous non-disjunction of the sex-chromosomes in Drosophila males.