Organogenesis and Cell Culture in Rice Plants under Sterile Condition ( Part II ) By EIZO MAEDA

Through observations of smear materials under a dissecting microscope, it was found that small smooth protuberances were produced in regions showing the dry appearance. Trichomes occurred in the regions showing the green color or the white and green color. There were tracheary elements having thickened wall in the inner part of callus, adjacent to which chloroplasts were observed11>. Scanning electron microscopy was done to observe nuclear envelop, nucleoli and fibrillar structure in nuclei in the cultured cellsl> . We thought, at first, a histological research of subcultured callus is an important prerequisite for evaluation of the inner structure of shoot-forming callus. As viewed by optical microscopy, there were several layers of densly stainable cells in the surface of callus and vascular-like elongated cells in the inner parts. From these results we called the callus growth with actively dividing cells in the surface as the first growth, and the growth with the meristematic cells in both the inner and the surface of callus, accompanied with differentiation and collapse in callus tissues, as the secondary growth. In addition, some root-like structure were also found in the callus tissues3>. From these results, further detailed observation was made during the growth process of Aichiasahi callus12>. The growth of compact Com1,ac1 C:.'lllus