The growth in our understanding in recent years of the class of pinocytic vesicles known as ‘coated vesicles’ has been substantial, as evidenced by the contributions of others to this volume. It is arguably in the sphere of biochemical and structural aspects of these vesicles, however, that this growth has been most rapid. It was only a few years ago, for example, that the cytoplasmic network on coated vesicles was thought to be merely protruding ‘bristles’ or ‘hairs’, or even that this structure observed in thin-sectioned material was an artifact of the tissue-processing procedure. Although some of the myths surrounding these ephemeral cytoplasmic organelles have been dispelled, there is still a long way to go before we can be fully confident of our interpretations of their structure and function.

Isolation of coated vesicles

Unlike the isolation of smooth pinosomes, the isolation of coated micropinocytic vesicles can be easily monitored by morphological methods, requiring only electron-microscopical observation for estimation of both purity and yield (Plate 1). In spite of this, it was not until 1969 that two groups of workers independently made attempts to isolate these subcellular organelles. The first group, that of Schjeide et al. (1969), isolated coated vesicles from oocytes by use of a simple pressing device, separating the vesicles from other components by density gradient centrifugation. The second group, that of Kanaseki & Kadota (1969), isolated vesicles from guinea pig brains.