Mitochondria aggregate aberrantly in spermatocytes and spermatids in mtsh^Z2-2620 homozygotes or mtsh^Z2-2620/mtsh^Z2-3484 males. Primary spermatocytes appear normal, but mitochondria aggregate abnormally early in late primary spermatocytes before meiotic divisions. As a result, mitochondria aggregate in a single shell surrounding each premeiotic nucleus instead of in a separate body beside each postmeiotic nucleus as in wild type. Mutant spermatocytes undergo karyokinesis with the resulting 4 nuclei staying adjacent to each other within a single mitochondrial shell. Meiotic cytokinesis is never observed, though spermatid bundle elongation and other subsequent events of spermiogenesis do occur. Spermatid tails appear irregularly packed. The resulting sperm cells are not individualized.

Aberrant meiosis I spindles are detectable in the subset of mtsh^Z2-2620 cells with aggregated mitochondria just before mitochondrial fusion: mtsh^Z2-2620 cells in meiosis I lack the overlapping astral microtubules in the central spindle region that are normally seen in wild type cells. The region corresponding to the anastral spindle is still intact, and some non-overlapping astral microtubules are present.

fzo²/fzo^z3-4436, mtsh^Z2-2620 has abnormal meiotic cell cycle phenotype

fzo²/fzo^z3-4436, mtsh^Z2-2620 has spermatocyte phenotype