<i>His2Av</i> is required cell autonomously for GSC maintenance.

<p>(<b>A–A′</b>): Apical tip of wild-type testis immunostained with anti-His2Av (red), anti-Vasa (green), and anti-Fas3 (blue). GSCs (arrows) identified as Vasa positive cells adjacent to the hub (yellow dashed line). (<b>B–B′</b>): Testes expressing Sa-GFP (green) to mark spermatocytes, immunostained with anti-His2Av (red), anti-GFP (green), and anti-Fas3 (blue). Inset shows spermatocyte nucleus with Sa-GFP marking the nucleolus and His2Av localized to the chromosomes; hub (yellow dashed line). (<b>C–D′</b>): Apical tip of wild-type testes immunostained with anti-His2Av (red, C–D′), anti-Tj (green, C) to mark CySCs (arrows, C, C′) adjacent to the hub (yellow dashed line) or anti-Eya (green, D) to mark cyst cells (arrowheads, D, D′). (<b>E–E′″</b>): Testes day 3 PCI immunostained with anti-GFP (green) to identify homozygous <i>His2Av⁸¹⁰</i> mutant GSCs (arrows), anti-His2Av (red), anti- Fas3 and Tj (blue) and DAPI (E′″); hub (yellow dashed line). Scale bars: 10 µm (<b>F</b>): Percentage of testes with <i>His2Av⁸¹⁰</i> mutant (red) or FRT 82B control (blue) GSCs scored at indicated times PCI.(<b>G</b>): Percentage of testes with <i>His2Av⁸¹⁰</i> mutant spermatocyte cysts in a genetic background either with (blue line, rescue) or lacking (red line, no rescue) a <i>His2Av-mRFP</i> genomic rescue transgene. Data shows average ± S.D.