Ultrastructural implications of pretreatment for successful cryopreservation of Oncidium protocorm-like body.

By applying pre-treatment with high concentrations of sucrose and glycerol prior to desiccation and subsequent freezing in liquid nitrogen, successful cryopreservation with high recovery rate was achieved in Oncidium PLB (protocorm-like body). Cellular and subcellular changes after each step in various cryopreservation regimes were examined to elucidate the mechanism of the beneficial effect of the pretreatment which confers resistance to desiccation and freezing.