Fig. 2. punt is required for maintaining GSCs in the Drosophila testis. All the testes are punt¹⁰⁴⁶⁰/punt¹³⁵ mutants and are labeled for Hts (green) and DAPI (blue) except nuclei of dying cells are labeled red in D. The hub cells are highlighted by circles, whereas GSCs are identified by broken lines. (A) The tip of a punt mutant testis one week after being cultured at 22°C showing eight GSCs. (B,C) The tips of two punt mutant testis one week after being cultured at 29°C showing one remaining GSC (B) or no GSCs (C). (D) The tip of a punt mutant testis 4 days after being cultured at 29°C showing that no GSCs undergo apoptosis except a few late somatic cyst cells (arrow). All the images are shown at the same magnification. Scale bar: 10 µm.