An ultrastructural study of carpospores in the red alga <Emphasis Type="Italic">Chondrus pinnulatus</Emphasis> (Harvey) okamura, 1930 (Rhodophyta: Gigartinaceae) from Vostok Bay,the Sea of Japan

The morphological features of carpospores in the red alga Chondrus pinnulatus have been studied using methods of transmission and scanning electron microscopy. Rounded mature carpospores are assembled into groups. Each carpospore is surrounded by a two-layered mucilage wall. The electron-dense cytoplasm contains numerous starch grains, fibrous vesicles, and large clusters of fibrous vesicles. The plastids have well-developed thylakoids and the cell nucleus occupies a nearly central position. The nucleolus is large and loose and is localized near the nuclear membrane. Dictyosomes, small fibrous vesicles, osmiophilic granules, and plastids are localized at the periphery. Mitochondria are arranged near the dictyosomes, plastids, and around the nucleus. A generalized scheme of the fine structure of the carpospore has been proposed for red algae on the basis of our own and literature data.