DISTRIBUTION OF AFFERENT FIBERS IN VENTRAL SPINAL ROOTS TO THE SPINAL CORD AND MEDULLA OBLONGATA / 解剖学报

ABSTRACT

After severance the ventral spinal roots in 10 dogs, the distribution of the anterograde degeneration was studied by means of Nauta's technique with the following conclusions:1. After sectioning the ventral roots, degenerating fibers (including preterminal and terminal fibers) appeared regularly in the spinal cord and medulla oblongata. This confirms that there are afferent fibers which project into the central nervous system via the ventral spinal roots.2. These degenerating fibers ascended not only in the posterior funiculi, but also in the gray matter, so that the preterminal and terminal degenerations of the terminal branches or collateral branches were found in the columna grisea posterior of the thoracic and cervical segments above the surgically operated segments of the spinal cord.3. The preterminal and terminal degenerations were found in the reticular areas of the nucleus gracilis of the medulla oblongata and around the non-cluster cells.4. Degenerating fibers were unequally distributed, most of them located ipsilaterally. The degenerating fibers decreased in number in rostral segments.5. Afferent fibers in ventral roots differ from those in dorsal roots in distribution:a) From the operated segment and to far more rostral segments, afferent fibers of the ventral root were distributed in a more medial position in the spinal dorsal gray column, viz, "medial tendency", and then ascended after interposing into the funiculi gracilis. This is different from the afferent fibers of the dorsal root in the control group which were distributed in "equal tendency" in the dorsal column and took a "lateral addition fashion" of entering the funiculi gracilis.b) Apparently, much more afferent fibers in ventral roots projected contralaterally than those in the dorsal roots.c) It was also characteristic that the afferent fibers in ventral roots projected further toward the rostral segments of the spinal cord.