Ciliated Schwann Cells in the Autonomic Nervous System of the Adult Rat

Recently several papers have appeared reporting the discovery of cilia on cells where they have not been suspected before, such as fibroblasts (20), chromaffin cells (6, 92), neurons (14, 22), tumor cells (3, 12), smooth muscle (20), renal epithelium (I 1), the parenchymal cells of the adenohypophysis (2) and the islets of Langerhans (13), and unidentified cells in the spleen of the chick embryo (3). These examples fall into three categories: (a) those in which the fine structure of the cilia is similar to that of ordinary motile cilia (12), (b) those in which the reports give insufficient detail for the analysis of the fine structure (3, 6, 11, 22), and (c) those which have one atypical feature in