Mutation of <i>Nxt1</i> leads to meiotic arrest in testes and failure of head eversion in pupae.

<p>(A) All stages of spermatogenesis are seen in wild type testes by phase contrast microscopy. Large round cells near the apical region (*) are primary spermatocytes, while spermatids elongated up the length of the testis (arrow). In <i>Nxt1^z2-0488</i>/<i>Nxt1^DG05102</i> mutant (B) or <i>Nxt1^z2-0488</i>/<i>Deficiency</i> (C) testes, only stages up to mature primary spermatocytes are present. (D) Hoechst fluorescence and (E) phase contrast images of wild type mature primary spermatocytes reveals a prominent nucleolus and distinct chromosome territories in each nucleus. (F) Hoechst fluorescence and (G) phase contrast imaging of <i>Nxt1</i> mutant spermatocytes reveals that the cells arrest with partially condensed chromatin and a prominent nucleolus. (H) <i>Nxt1</i>/+ pupae had everted spiracles, and distinct head, thorax and abdomen (h, t, a), while <i>Nxt1</i> mutant pupae (I–K) often had only partially everted spiracles, and the thorax was at the extreme anterior of the pupal case. Many mutant pupae were also curved (J).