"Hyperdiploidy" in the Purkinje neuron population: chromatin status or extra-DNA? The influence of fixatives on Feulgen-DNA.

The influence of different fixatives (4% formaldehyde, methanol-acetic acid, methanol-formalin-acetic acid) and hydrolysis kinetics (performed at 23 degrees C and 60 degrees C) on the chromatin availability to the Feulgen reaction of cerebellar Purkinje neurons has been examined. The results show that formaldehyde preserves or even emphasizes the different availability to histochemical reactions for the detection of DNA. The existence of great heterogeneity in the Purkinje cell population, which cannot be detected in granule cells, is once again confirmed. The fact that mean values of DNA content are generally lower in granule cells than in Purkinje cells does not allow us to exclude that at least a small percentage of the highest values might be due to an actual extra DNA synthesis to a different extent.