SELECTIVE FLUORESCENCE OF EOSINOPHILIC STRUCTURES IN GRASSHOPPER AND MAMMALIAN TESTIS STAINED WITH HEMATOXYLIN-EOSIN

After staining with Mayer's haematoxylin and eosin Y, paraffin section s of grasshopper and mouse testis were analysed by both transmitted li ght and fluorescence microscopy. Under violet-blue (436 nm) light exci tation, a bright green emission was observed in all eosinophilic struc tures. Meiotic spindles (fibres and poles), mitochondrial aggregates, centriolar adjuncts in grasshopper spermatids, the basal lamina, flage llar bundles and remaining cytoplasmic droplets in the lumen of semini ferous tubules showed the most striking fluorescence induced by eosin Y. No emission was found in these structures after haemalum staining. Fluorescent microtubular components also revealed a positive immunoper oxidase reaction for alpha-tubulin. All fixation and embedding procedu res (Bouin, Zenker, formaldehyde alone or followed by dichromate or gl utaraldehyde, freeze-substitution) were suitable for observation by fl uorescence microscopy. Acetylation, deamination, and prolonged washing of stained sections with water, salt solution or ethanol strongly red uced eosin Y fluorescence, while it slightly increased after methylati on. These results show that routine haematoxylin-eosin stained tissue sections can be routinely analysed by fluorescence microscopy. The emi ssion of eosin Y allows easy and precise recognition of eosinophilic s tructures, which are poorly visible under bright field illumination.