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Publisher Summary This chapter explains cytoenzymological methods and isozymes. Cytohistochemistry has grown rapidly since 1939, when Gomori and Takamatsu devised the technique for demonstrating phosphatases in tissue sections; before 1939 its growth was slow and sporadic. Free-living cells have intact plasma membranes that are highly impermeable to many enzyme substrates in cytohistochemical techniques, because of their high electrical resistance and their highly complex structure and organization of the cell periphery. Prolonging the incubation time, beyond the relatively short periods suitable for enzyme histochemistry of tissue sections, enabled enough increments of substrate to permeate the intact plasma membranes of free-living cells so that the total became sufficient to yield ample amounts of enzyme reaction products. There has been preoccupation in histochemistry with the strong fixatives used in histology to achieve immobilization, perhaps because of the influence of more than a century of development of histological stains. Brief immersion in cold absolute acetone added precision to the histological detail, and also helped to retain cells on the glass slides. |
