MT and chromatin organization in aust spermatocytes. (A) Wild-type and aust primary spermatocytes stained for α-tubulin (green) and DNA (blue). In mutant cells, chromosomes fail to align on the metaphase plate and are irregularly segregated during anaphase. Although meiotic spindle morphology appears normal, the central spindle is absent during both anaphase and telophase. (B) Wild-type and aust testes prepared to visualize chromosome morphology. In contrast to wild-type cells, aust spermatocytes in prometaphase I show separation of sister chromatids (arrows). (C) Wild-type and aust spermatocytes stained with antibodies to α-tubulin (green), phosphohistone H3 Ser¹⁰ (red), and DNA (blue). In both wild-type and aust cells, histone H3 is phosphorylated upon entry into meiosis I and II and dephosphorylated by telophase. Bars, 10 μm.