dind²⁸⁷⁰/Df(3R)BX5 transheterozygous third instar larvae present smaller brains with reduced numbers of dividing cells (decrease in BrdU labelling) that show a metaphase delay (increase in mitotic index but decrease in proportion of cells in anaphase or telophase), as compared to controls. Mitotic brain cells exhibit defects in chromosome number and morphology that are virtually absent in controls: frequent hyperploidy and polyploidy, and less frequent chromosome endo-replication; frequent unevenly or over-condensed chromosomes; and several types of chromosome aberrations, such as chromatid deletions, isochromatid breaks, and complex rearrangements. Mitotic brain cells also exhibit poor chromosome alignment, distorted spindles and defective centrosome number, as compared to controls.

Likewise, spermatogonia in dind²⁸⁷⁰/Df(3R)BX5 transheterozygous third instar larvae are much frequently in metaphase than controls and these metaphases display frequent defects that are virtually absent in controls: significantly longer spindles; irregular number of centrosomes; frequent unevenly or over-condensed chromosomes; and frequent hyperploidy/polyploidy and chromosome aberrations. Mature primary spermatocytes also exhibit some defects that are virtually absent in controls: centriole integrity defects; highly frequent detachment of asters from the chromosome-attached spindle; and frequent mis-orientation between the two daughter nuclei and the spindle axis at telophase. Unlike controls, onion stage spermatids in dind²⁸⁷⁰/Df(3R)BX5 transheterozygous third instar larvae show abnormally sized nuclei and Nebenkern, and the association between these two structures is generally lost, but abnormal spermatids are able to differentiate and produce sperm with long axonemes.