Parasagittal patches in the granular layer of the developing and adult rat cerebellum as demonstrated by NADPH-diaphorase histochemistry.

The development of nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) activity in the rat cerebellum was studied histochemically. NADPH-d reactivity was observed in the internal granular layer and some Purkinje cells by the end of first postnatal week (PW1). By PW2, the staining was localized in the granular layer (GL) and the molecular layer (ML), but not in the Purkinje cell layer. The staining in GL and ML increased further, and parasagittally organized NADPH-d patches in GL were recognizable by PW3. These patches were more distinct and almost adult-like by PW4. These results provide the first evidence of a patchy organization of NADPH-d activity in GL and suggest that NADPH-d plays an important role in the maturation and function of the cerebellum.