Fig. 7.1. A degenerating myelin sheath in layer 4 of area 46 in a 35 year old monkey. The axon of the nerve fiber is intact, but the myelin sheath is bulging out to one side. It is difficult to know if this is a real balloon produced by splitting of the intraperiod line of the sheath or an inclusion of dense cytoplasm that contains a large vacuole.
