Fig. 6. Gametogenesis. (A) Sagitta bipunctata: two PGCs above the transversal septum (TS) will give the female germ cells of the two ovaries; the two PGCs below will yield the male germ cells of the two testes (see also Fig. 5F). (B) Sagitta bipunctata: the four PGCs (arrows) are labelled with Drosophila anti-Vasa antibody. (C) Sagitta bipunctata: the four PGCs have proliferated (4 days after fertilization). (D) Sagitta bipunctata: thin section of one of the four first PGCs. Characteristic electron-dense material (arrows) is sandwiched between the nucleus (N) and a ring of mitochondria (M). (E) Spadella cephaloptera: thin section of proliferating PGCs containing dispersed electron-dense material (arrows). (F) Spadella cephaloptera: Drosophila anti-Vasa antibody localization in oocytes (peroxidase detection). (a,b) The GVs of oocytes are surrounded by patches of Vasa-positive material. Three of these patches are indicated by arrows in b. (c) A higher magnification view of the Vasa-positive patches (arrows) at the level of the GV surface (tangential view). (d) Control; view of a GV stage oocyte exposed to HRP-labelled secondary antibody only. (G) Sagitta inflata: thin section of a portion of an oocyte GV showing the electron-dense material on both side of the nuclear pore-rich GV membrane (arrows). (H) Spadella cephaloptera: Immunoblots with Drosophila anti-Vasa polyclonal antibody using three eggs, three embryos or three juveniles, representing similar amounts of protein in each lane. An increasing amount of Vasa-like protein is visualized using two different detection methods (ECL/Vectastain peroxidase kit).
