FLUORESCENCE MICROSCOPY OF RAT EMBRYO SECTIONS STAINED WITH HEMATOXYLIN-EOSIN AND MASSONS TRICHROME METHOD

The fluorescence pattern induced by haematoxylin-eosin (HE) and Masson 's trichrome (MT) staining methods on paraffin sections of rat embryos (from 13 to 18 days old) has been studied, Using optimal excitation ( green light, 545 nm), HE- or MT-stained sections showed a selective re d emission of the acidophilic tissue components, which was due to eosi n Y in the case of HE and to acid fuchsin and/or xylidine ponceau in t he case of MT. The fluorescence intensity induced by these anionic dye s was variable and related to the substrate nature and the embryo age, Whereas in young embryos only the immature red blood cells showed a n oticeable fluorescence, in the oldest embryos there were also other ti ssue components that selectively fluoresced with these dyes, in partic ular fibre lens cells, elastic fibres, zymogen granules and muscle cel ls. Spectrofluorometric studies on free dyes and densitometric analysi s of protein blots confirmed microscopical observations, Our results i ndicate that the standard HE and MT staining methods can be used in re cognizing the appearance of specific protein structures in embryonic t issues by means of fluorescence microscopy.