Mature plurilocular sporangia of Cladosiphon okamuranus

Tokida were collected from their natural habitats in Okinawa Island

Japan

and cultured under laboratory conditions.Light and transmission electron microscopy were employed in studying the structure and ultrastructure of sporophytes.Germlings of sporophyte are developed from discoids.Assimilatory filaments aroused from discoids are miniliform

comprising about 15 cells.At the intermediate parts

the assimilatory filaments are found to be branched.Basal cells of many assimilatory filaments are parallel and hollow

and form pseudoparenchyma

when germling turns to elongation growth period.At the apical end of some assimilatory filaments

unguiform plurilocular sporangia engender.Transmission electron micrographs revealed that several chloroplasts and mitochondria exist in each discoid cell and assimilatory filament.Each chloroplast possesses single pyrenoid.Lipid bodies are seen in the chloroplasts.While as to assimilatory hair cells

there are less chloroplasts and mitochondria clinging to plasmalemma.Plasmoloization is apparent with many paths through the cell wall.