A more detailed mechanism to explain the "bands of Fontana" in peripheral nerves

Introduction. In 1779 Fontana identified transversal and oblique bands along peripheral nerves. Subsequent studies pointed alternatively at endoneural or perineural components as the cause. We wanted to sort out these conflicting findings. Methods. Recoiling of the bands was video-recorded in rat sciatic nerve. Computer Assisted Design (CAD) was used to model the nerve by interference figures. Results. In-vivo microdissection showed distinctive black and white highly packed bands in the perineurium, which differentiated them from widely spaced, translucent dark grey - pale grey, staggered bands in the endoneurium. CAD-merging these two patterns produced images resembling the bands in-vivo. Discussion. Two repetitive structures with different characteristics, one in the perineurium and another in the endoneurium, merge to give the appearance of the bands.