GRANULATED UNMYELINATED NERVE FIBERS IN PINEAL REGION OF ANURANS

The anuran pineal region, which includes the connective tissue capsule of the pineal organ and adjacent parts of brain, shows many unmyelinated nerve fibers. Most of these fibers have a perivascular location. Many of the fibers contain inclusions resembling synaptic vesicles as well as dense-core vesicles of granular appearance with diameters of either 500-1,000 Å or 2,000 Å. Isolated granulated fibers penetrate into the synaptic regions of the pineal organ. It is suggested that this extensive fiber system may be damaged during pinealectomy and that adjacent tissues containing fibers with granular inclusions may contaminate the pineal extracts. This may lead to false conclusions about the function of anuran epiphysis. © 1968 Springer-Verlag.