THE CENTRIOLE - TWIST AND PITCH - TOWARDS A 3-D RECONSTRUCTION

A comprehensive description of the overall organization of the centros ome in animal cells is still lacking. In order to integrate the variou s pieces contributing to the centrosome structure, we have undertaken an extensive ultrastructural study of centrosomes isolated from human lymphoblasts. Our approach, which involved ultrathin serial sectioning and a quantitative image analysis of the micrographs, gave a detailed description of the centriolar and pericentriolar regions. In this wor k, we focussed our attention on the geometrical relationships between the successive serial sections of centrioles in order to obtain quanti tative informations upon the 3-D arrangement of microtubules.