Newly eclosed mutant males contain the same number of germline stem cells per testis as newly eclosed wild-type males. However, the number of germline stem cells per testis in aged (10 day old) males is reduced compared to wild type. The number of early germ cells (stem cells, gonialblasts and spermatogonia) is reduced in 3 day old mutant males compared to wild type.

Mutant males have reduced fertility compared to wild-type males when compared each day for the first 10 days after eclosion. On days 1 to 3, the mutant males produce 40-50% of the number of offspring produced by wild-type controls, while males older than 3 days produce only 20-30% of the offspring produced by wild-type controls.

OdsH⁰ flies show no observable defects in viability, morphology or fertility in the absence of rigorous experimentation. Subtle fertility defects have been assayed using a sperm-exhaustion assay on young males; each male is given three virgin females at 2 days of age and on every day afterward and the number of offspring produced by the females on each day of mating is counted. In this assay, the fertility reduction in OdsH⁰ males compared to wild-type males is 61%, 45% and 13% as males age from 2 to 3 to 4 days. This fertility effect is significant on days 2 and 3, but is not significant on day 4.