Fig. 3.3. Transverse section through the corpus callosum of a 6 year old monkey. At this higher magnification the lamellae of the myelin sheaths are visible and in some cases the inner and outer tongues of cytoplasm of the sheaths are apparent. When these myelin sheaths are carefully examined and the spiraling of the lamellae followed from where the lamellae begins on the inside of the sheath at the inner cytoplasm tongue process and ends at the outer tongue process, it will be seen that in some cases the spiraling is clockwise and in other cases it is anticlockwise. Two paranodes are labeled, as well as a profile of a nerve fiber in which the plane of section passes through the junction between the paranode and the node. Myelin sheaths of the central nervous system are difficult to preserve and so splitting is not uncommon, especially in the thicker sheaths.
