Figure 2b. Electron microscopic features of LCs. (a) Drawing of an LC shows numerous surface dendritic processes, a convoluted nucleus, and a prominent nucleolus. Rod-shaped Birbeck granules (inset) characteristically have a pentalaminar appearance with a zipperlike central axis. Dilatations at the rod ends give granules their characteristic tennis racquet appearance. (b) High-power electron photomicrograph demonstrates Birbeck granules located near the cell nucleus. Note parallel linear structures separated by finely granular material and a terminal expansion producing the tennis racquet appearance.