Pinocytosis in the Rabbit Corneal Endothelium

Abstract

<h3>Introduction</h3> In view of the demonstration that rabbit corneal epithelium actively transports sodium,^1,2a preliminary electron microscopic study of this structure was undertaken. Previous electron microscopic studies had been primarily concerned with the characterization of the fibrous components of the cornea, and the specialized staining used to study these fibers did not present the cellular elements to best advantage. It was hoped that by examining unstained preparations a possible anatomic site for such active transport might be identified or that, at least, pinocytosis might be seen in the epithelium as a conceivable mechanism by which sodium ions are transported across this multicellular layer. The results of this attempt were disappointing: although clear electron micrographs of the epithelium were readily obtained, no structures suggestive of pinocytosis were demonstrated. An examination of the endothelium not only confirmed Speakman's³and Jakus'^4,5observations of numerous mitochondria in these cells but also