Ultrastructure and organelle distribution in adult ovine COCs. Representative TEM micrograph showing a well developed cup-shaped Golgi complex (G), in close proximity to the smooth endoplasmic reticulum (SER) and round, ovoid or hooded mitochondria (m). Irregularly shaped and electron-lucent vacuoles (Va) are delimited by a discontinuous membrane. Arrow: a hooded mitochondrion; asterisks: mitochondria with the so-called “clear vesicle” inside. CGs: round, electron-dense cortical granules; mv: microvilli; PVS: perivitelline space. Bar: 1 μm.