DIFFERENTIAL STAINING OF 2 SUBPOPULATIONS OF PURKINJE NEURONS IN RAT CEREBELLUM WITH ACID DYES

We present a new method that stains differently two subpopulations of Purkinje cells in the adult rat. Deparaffinized sections of cerebella, fixed by perfusion with buffered glutaraldehyde or Bouin's fluid were stained with 0.5% light green in 50% ethanol (10-30 min). The excess dye was removed with saturated aqueous picric acid (10-30 min). At thi s point some Purkinje cells appeared as lightly stained neurons, while others were strongly stained. Slides were immersed in 0.5% aqueous ac id fuchsin for approximately 1 min until the lightly stained neurons a cquired a red color. Following immersion in 1% phosphotungstic acid, s lides were rapidly dehydrated in ethanol, passed to xylene and mounted in Canada balsam. Two subpopulations of Purkinje cells differing in t heir protein content in somata and proximal dendrites stained differen tially by this method. They occurred in all coronal and sagittal secti ons and in patches or stripes. Their relative proportion varied from l obule to lobule. A second staining method used potassium permanganate as the sale staining reagent. The staining reagent can be used on sect ions previously stained with the acid dyes. Purkinje cells appeared as subsets of brownish to deep brown stained neurons, the latter ones co rresponding to green stained cells in the dichromic method. The result s obtained indicated that the subpopulations reflect real differences among individual neurons and are not artifacts. The technique holds pr omise for identifying and localizing subsets of Purkinje cells differi ng in their protein content under normal and experimental conditions a nd for their further characterization by combined staining and histoch emical procedures.