A schematic representation of an ovariole of D. melanogaster . A, an ovariole of D. melanogaster consisting of the germarium (g) and the vitellarium. B, a detailed scheme of the germarium structure composed of regions 1, 2a, 2b, 3. The checkpoint is framed (red). C, a 16-cell cyst; SSCN, a somatic stem cell niche; SSC, a somatic stem cell; FC, a follicle cell.