Selective staining by the fluorochrome 5,5 '-diphenyl-9-ethyl-oxacarbocyanine. II. Application to paraffin embedded nervous tissue

We present a simple and rapid method to label specific structures of neural tissue in paraffin sections. After incubation of deparaffinized sections i n the cyanine dye 5,5'-diphenyl-9-ethyl-oxacarbocyanine (DEOC), three diffe rent washing and mounting procedures were performed. Incubation in DEOC fol lowed by washes in ethanol and water and mounting in glycerol-gelatin resul ted in selective labeling of myelin in the central and peripheral nervous s ystems. Weak labeling of myelin and axons and staining of nuclei of neurons was seen after incubation in DEOC followed by washes in ethanol and xylene , and mounting in Eukitt. Nuclear proteins, the endoplasmic reticulum and t he Golgi apparatus were stained strongly and exclusively after incubation i n DEOC, washes in water, ethanol and xylene, and mounting in Eukitt. Thus t he absorption pattern of DEOC is changed significantly by solvents applied after the fluorochrome. In any case, fluorescence did not fade even after r epeated and intense fluorescence microscopy over a period of 6 months.