Review Article : Molecular and genetic changes associated with cell proliferations and methods for visualizing these processes by light microscopy with the aid of non-isotopic labeling.

A combination of enzyme histochemistry and immunology opened a new era of cyto-and histochemistry, i. e. enzyme immuno-histochemistry. With this newer technique, it became possible to visualize under the ordinary microscope a number of gene products as long as appropriate antibodies against these were available. In this review, the authors tried first to summarize the current knowledge on the molecular and cytologic events associated with cell proliferations. These included the chromatin changes during S and M phases, nucleolar alterations by the action of the nucleolar organizer region (NOR), and various growth factors, receptors and intracellular information transmitting systems for the cell proliferation. Secondly, various histo- and cytochemical methods for visualization of these molecules were reviewed with regard to their principles, advantages and disadvantages and technical feasibilities. The discussions and considerations were illustrated by the microsopic photographs by the alkaline phosphatase-labeled avidin-biotin method followed by hexazotized new fuchsin coloration technique developed by one of the authors. Thirdly, a combination of enzyme immunohistochemistry and recently developed techniques of molecular biology, i. e. DNA hybridization and DNA amplification with polymerase chain reaction (PCR) was discussed in theory and practice. The combination of DNA hybridization method and enzyme immunohistochemistry resulted in the in situ hybridization (ISH) method, and it was demonstrated that the method worked beautifully when used in conjunction with alkaline phosphatase-labeling and new fuchsin coloration with methylgreen counterstain. The PCR method was superb for the in vitro amplification of a gene and its detection. For its application to ISH, however, there were several basic problems to be solved and these were discussed together with future prospects of its potential applicabilities