Fig. 7. Effect of antisense oligonucleotides injection on the ultrastructure of germ plasm in mature oocytes. Electron microscopy images of germ plasm islands in the vegetal cortex of matured oocytes. In control (A), antisense XlCaax ODN (B), antisense Xlsirts ODN (C) and VegT morpholino (D) -injected oocytes, germ plasm islands contained tiny electron-dense germinal granules (arrows) located between mitochondria (m). In oocytes injected with antisense VegT ODN (E), the germinal granules coalesced precociously, forming stringy large aggregates (arrows). These aggregates resembled germinal granule aggregates, which normally occur in four- to eight-cell embryos. Y, yolk; CG, cortical granules. Scale bars: 400 nm.