Transmission electron micrographs of high-pressure frozen, cryosubstituted and Epon-embedded G. obscuriglobus at different budding stages. A. The ICM of the bud is continuous (arrowheads) with the mother cell ICM through the bud neck during an early budding stage. No nucleoid is visible in the bud at this stage. B. Condensed nucleoid is visible in this more matured bud and double membrane nucleoid envelope (NE) is visible in some places. The nucleoid envelope does not yet completely surround the nucleoid. The arrows indicate several regions at which ICM of the bud is continuous with the outer membrane of the nucleoid envelope. C. Budding cell displaying the origin of the double-membrane nucleoid envelope (NE) surrounding the nucleoid (N). The mother cell ICM displays continuity (arrowheads) to the inner membrane of the nucleoid envelope, and the bud ICM shows continuity (arrows) to the outer membrane of the nucleoid envelope. Bar – 200 nm.