Morphology of Mitochondria in Syncytial Annelid Female Germ-Line Cyst Visualized by Serial Block-Face SEM

Figure 1

Organization of the germ-line cysts in the E. albidus ovary. (a) Several almost spherical cysts are visible within the entire ovary. The cysts are composed of germ cells in successive stages of oogenesis. Initially, all of the germ cells within the cyst were undifferentiated (dotted line), but in the later stages (bracket), one growing oocyte (O) and several of the 15 smaller nurse cells (NC) were visible in the cysts; Cy – cytophore. (a)–(c) The organization of the germ-line cysts was always the same: the germ cells were located at the cyst periphery (both the nurse cells – NC and the oocyte – O) and each one was connected to the centrally located mass of cytoplasm, the cytophore (Cy) via one open cytoplasmic channel called a ring canal (arrows). Rhodamine-conjugated phalloidin staining showed that the ring canal rim was rich in F-actin. Light microscopy, (a) Epon semi-thin sections stained with methylene blue, bar = 10 µm; (b) whole-mounted preparation, Nomarski interference contrast, bar = 30 µm; (c) the cysts double stained with DAPI (blue) and rhodamine-conjugated phalloidin (red), bar = 5 µm.