Abstract:Cells were isolated after enzyme treatment from the thalli of Porphyra yezoensis Ueda and cultured in enriched seawater media (MES). Cultures were put in an incubator with light intensity of 2000--2500 lx from cool-white flurescent lights and were maintained on a 12:12 LD cycle. The temperature was 20±2℃ and the media were changed weekly. Two main types of differentiation and development ways in cultured cells under light microscope: 1. Cells directly formed the single cell seedlings Eke monospores; 2. Cells first divided into cell aggregates, then released lots of spores that could germinate into sporelings. Both single cell seedlings and sporelings were called cell seedlings. So it is possibole to breed from the ceils isolated directly from the thalli in Porphyra yezoensis.