EVIDENCE FOR THE LYSOSOMAL NATURE OF THE PAS-POSITIVE GRANULES IN THE PURKINJE CELL OF THE CEREBELLAR CORTEX IN THE ADULT CAT

Abstract

In the adult cat, the Purkinje cell of the cerebellar cortex contains PAS-positive granules distributed more or less at random within the pericaryone and the primary dendritic branches. In the present study, evidence has been obtained indicating that such granules exhibit enzymatic activities characteristic of the cytoplasmic organelles known as lysosomes. Frozen sections of the cerebellar cortex, fixed in chilled formol–calcium and stained according to histochemical procedures for the detection of acid hydrolases, indeed reveal that the granules in question possess high levels of acid phosphatase, ribonuclease, deoxyribonuclease, and arylsulphatase activities. Further support for our conclusion comes from electron microscope observations of osmium-fixed material which show that the PAS-positive granules are solid organelles possessing ultrastructural features characteristic of the lysosomes in general. These features include a single, usually complete, limiting membrane; a 70 to 100 Å wide electron-transparent zone separating the limiting membrane from the organelle matrix proper; a matrix consisting of a fine, rather homogeneous, grainy material of moderate electron opacity which often contains ill-defined masses or clumps made up of a more electron-dispersing substance.