Males carrying l(1)dd4³ can develop to adults in favourable culture conditions. Fewer l(1)dd4³ males eclose than l(1)dd4^S males when hemizygous, suggesting that l(1)dd4³ is more severe than l(1)dd4^S. l(1)dd4³ males are infertile and are found to produce immotile sperm. Primary spermatocyte cysts from l(1)dd4³ testes often have fewer cells compared to wild-type. Some of the cells are larger than the others, whereas the morphology of both germline and somatic cells seems normal. l(1)dd4³ primary spermatocytes exhibit abnormalities in the morphology of the meiotic spindles. Cysts of early spermatids in l(1)dd4³ display fewer than 32 Nebenkerns with abnormal morphology and variable size. The abnormal meiotic divisions can result in onion stages with only 16 cells. 16-cell cysts at the onion-stage with a 1:1 ratio of nuclei to Nebenkerns are found more frequently in l(1)dd4³ than in l(1)dd4^S males. In general, l(1)dd4³ showed a stronger hypomorphic phenotype than l(1)dd4^S, mainly reflected in the relative viability of adult males, the number of early spermatid cysts with 4N nuclei, and the presence of sperm tails inside the testes. Chromatin has a scattered distribution during meiosis in l(1)dd4³ mutants.