Fig. 2. The generation of a niche during gonadal development. (A) An early pupal gonad (0-2 hours after puparium formation) showing the disposition of terminal filament cells and cap cells, and germline cells. This focal plane depicts five ovarioles. (B,C) Magnification of ovarioles from 0-2 hour pupal gonads. (B) Germline cell in metaphase. The mitotic spindle is oriented so that one of the daughter cells will remain in contact with the cap cells. (C) Cystoblast dividing; the mitotic spindle of these differentiating cells is oriented randomly with respect to the cap cells. In this particular case it is perpendicular to the anterior-posterior axis of the ovariole. Red: tubulin staining to show cell shapes and mitotic spindles; green: membrane-bound GFP driven by a germline specific promoter to label germline cells; blue: phosphohistone H3 to label dividing cells.