Figure 5.—

Cytological evidence of chromosomes with double crossovers. (A) DAPI-stained chromosomes in a diakinesis-stage oocyte nucleus from a hermaphrodite homozygous for the mnT12(IV; X) two-chromosome fusion; image is a projection of a 3-D data stack encompassing all chromosomes. The fusion chromosome bivalent is indicated by the arrowhead; the ring-like configuration of this bivalent is most easily explained by the presence of two chiasmata. Bar, 3 μm. (B) Table indicating the incidence of diakinesis nuclei containing a ring-shaped bivalent in mnT12 and him-3(me80) mnT12 animals.