LOCALIZATION OF BETA-D-GALACTOSIDASE ACTIVITY IN SEMITHIN EPON SECTIONS OF EMBRYONIC-TISSUES USING DIFFERENTIAL INTERFERENCE CONTRAST OPTICS

In the present study we describe a method for the histochemical demons tration of beta-D-galactosidase activity on tissue sections processed for light microscopy at high resolution. 5-Bromo-indolyl-beta-D-galact opyranoside (Bluo-Gal) was utilized as an indigogenic method for the d emonstration of Escherichia coli beta-D-galactosidase reporter gene ac tivity whose expression was studied in a transgenic line where the enz yme, with a nuclear localization signal (nlacZ), is under the transcri ptional control of a striated muscle-specific promoter. At the light-m icroscopic level, by using Differential Interference Contrast (DIC) op tics, the reaction product was detected as precipitates in the form of fine birefringent crystals. These were located around and inside the nuclei of beta-gal-expressing cells. This simple method allows an easy and rapid identification of few or even one labeled cell(s) within la rge microscopic fields (whole embryos) and the labeled cell(s) can be evaluated both morphologically and quantitatively.