Bivalent Structure in the Fly, Melophagus Ovinus L. (Pupipara, Hippoboscidae)

Abstract

In meiosis of Melophagus homologous autosomes join over only a short portion of their lengths; unpaired parts of homologues lie apart at diakinesis. Before and at meta-phase there is a state of tension between the spindle attachment and the points of association. As a result the autosomal bivalents simulate chiasmata; the relatively minute pairing regions are merely chromosomal foci to which somatic pairing forces are restricted and which by exaggeration hold the bivalents together at meiosis.