Cytochemistry of kinetochores under electron microscopy

Abstract

A cytochemical analysis has been performed on kinetochores of mouse, Allium and grasshopper under the electron microscope. The study was carried out using serial sections and cytochemical methods. Alcoholic PTA was used for basic protein staining and the EDTA method for preferential staining of ribonucleoproteins. In mouse and Allium chromosomes the kinetochore appears positively stained after PTA and EDTA. In grasshopper chromosomes, kinetochores appear as a fibrillar and less dense region and are positively stained after EDTA. Blocks from mouse treated with HCl prior to PTA stain show lower contrast in the kinetochore. When Allium cepa anthers were treated with RNase and perchloric acid (PCA) there was no positive effect after EDTA stain in the kinetochore region. It is suggested that non-DNA material takes part in the constitution of the kinetochore. This material would be made up, at least in part, of basic proteins and ribonucleoproteins.