Significance of 'in vivo cryotechnique' for morphofunctional analyses of living animal organs.

Our final goal of morphological and immunohistochemical studies is that all findings examined in animal experiments should reflect the physiologically functional background. Therefore, the preservation of original components in cells and tissues of animals is necessary for describing the functional morphology of living animal organs. It is generally accepted that morphological findings of various organs were easily modified by stopping their blood supply. There had been a need to develop a new preparation technique for freezing the living animal organs in vivo and then obtaining acceptable morphology and also immunolocalization of original components in functioning cells and tissues. We already developed the 'in vivo cryotechnique' (IVCT) not only for their morphology, but also for immunohistochemistry of many soluble components in various living animal organs. All physiological processes of cells and tissues were immediately immobilized by IVCT, and every component in the cells and tissues was maintained in situ at the time of freezing. Thus, the ischaemic or anoxic effects on them could be minimized by IVCT. Our specially designed cryoknife with liquid cryogen has solved the morphological and immunohistochemical problems which are inevitable with the conventional preparation methods at a light or electron microscopic level. The IVCT will be extremely useful for arresting transient physiological processes and for maintaining any intracellular components in situ, such as rapidly changing signal molecules, membrane channels and receptors.