Excised explants from & strains of Porphyra yecoensls thalli were cultured. In spite that many cells were necrotic dur- ing the culture, all the & strains regenerated their seedling in different ways: (1)marginal cells formed sporangia contain- ing several spores; (2)scattering survived cells contracted and extracellular matrix thickened to form monospores; (3) cells developed into callus-like clumps then to the differentiated young plantlets.