Common immunohistochemistry is a technique based on antigen-antibody reactions in thin sections. It is well known that the important steps of tissue preparation protocols are (i) fixation (chemical and physical methods, especially cryofixation), (ii) sectioning, and (iii) immunostaining. We have already examined how to combine these preparation steps for an improved immunohistochemistry of target cells and tissues so as to overcome some of the technical problems commonly encountered. In many experimental cases, various cryotechniques were useful to obtain both a strong immunoreactivity of the antigens and a high time-resolution of the morphology of living animal cells and tissues. When the ultimate aim is to obtain in vivo observation of the morphology and immunolocalization, the new concept of in vivo cryotechnique becomes indispensable in the field of cell biology.