Modern histochemical methods using enzymes as markers.

Abstract

In the 25 years since the idea that histochemically detectable enzymes could serve as a marker of ligands, the world of histochemistry has undergone a dramatic change. Today slides of immunostained tissue sections may be filed together with hematoxylin- and eosin-stained slides and may be examined at one's leisure. Antigens are now localized at the ultrastructural level as well as at the light microscopic level permitting one to wonder about the intricacies and beauties of living creatures. Genes which mandate our body since the day of conception to the day of death can now easily be probed with enzyme markers. Even with all these success stories, some dreams which I had hoped to accomplish with the method are not yet realized. Unlike the chemical and physical properties of inert objects, living organisms are provided with a fixed genetic program. By recognizing the point in the program which is being executed, one can deduce the potential FUTURE activities of the cells and tissues. I hypothesize that this is not an impossible task since (1) histochemistry and immunohistochemistry already provide us information on the PAST activities of cells and tissues, (2) in situ hybridization describes PRESENT gene activities, and (3) newer methods allow for the determination of potential gene function. Thus it is possible to peek at the future.