Fig. 3. Vis/Achi expression during male meiosis. All images are of wild-type testes stained for Vis/Achi (green), Aly (blue or white) and DNA (red). (A) Low magnification view of an entire testis. Vis/Achi and Aly are most highly expressed in the primary spermatocytes. (B) High magnification view of the apical tip and immature primary spermatocyte stages. Weak Aly and Vis/Achi staining is observed in the nuclei of the mitotically dividing cells (yellow arrows) and in the nuclei of immature primary spermatocytes (white arrows). (C) A cyst with mature primary spermatocytes. The DNA is present as three diffusely staining regions per nucleus (white arrows), which correspond to the three main chromosomes bivalents in Drosophila. Both Aly and Vis/Achi are highly expressed in these nuclei. (D) A cyst in metaphase of meiosis I. The DNA is compacted into 1-3 dots per nucleus. Aly appears associated with the spindle (white arrow) and Vis/Achi appears to be primarily cytoplasmic (yellow arrow). (E) A cyst in metaphase of meiosis II. The DNA, Aly and Vis/Achi signals are similar to that seen at metaphase of meiosis I (D). (F) An `onion stage' cyst. Meiosis is completed, and spermatid differentiation has begun by the 64 haploid progeny. Nuclei (white arrows) are closely paired to round, specialized mitochondria (yellow arrows). At this stage, the DNA is present in one dot per nucleus, Aly is tightly associated with the DNA (also in one dot/cell) and Vis/Achi is observed throughout the cell, but is excluded from the mitochondria. (G) At a later stage in spermatid differentiation, the DNA is less compact and is associated with Vis/Achi (arrow) whereas only background Aly staining is observed.