Introduction

Abstract

Morphological studies with light or electron microscopy and scanning probe microscopy have been major approaches to understand physiological and pathological features of living animal organs. Although other rapid progresses of research techniques in molecular or genetic biology have been realized to establish new molecular or biological fields, morphological techniques are still necessary for more precise understanding of living animal organs. For routine morphological analyses, both chemical fixation and alcohol dehydration have been commonly used to keep cells and tissues, but they always bring about many morphological artifacts, including tissue shrinkage and extraction of components. To the contrary, both quick-freezing and high-pressure freezing methods of resected fresh tissues have been also contributed to reduction of such morphological artifacts, but they have to be resected from living animal organs with blood supply. The in vivo cryotechnique (IVCT) has been found to be extremely useful to arrest transient physiological processes of cells and tissues and also to maintain their intra- and extracellular components in situ. The IVCT has already allowed us to perform novel morphological investigations of cells and tissues in living animal organs and will further contribute to new medical and biological fields with “living animal morphology.”