Cryopreservation of Dunaliella salina and Platymonas helgolandica var. tsingtaoensis A Simple and Rapid Cryo-sectioning Method in Plant Tissue Studies on Cryopreservation Technology of Shoot-tips of Garlic by Vitrif ication Studies on Cryopreservation Technology of Shoot-tips of Garlic by Vitrif ication CRYOPRESERVATION OF PLANT TISSUE CULTURES Cryosectioning technique for cytological studies in Kosteletzkya virginica