INTERNODAL LENGTH IN VENTRAL ROOTS OF BOVINE SPINAL NERVES VARIES INDEPENDENTLY OF FIBER CALIBER

  • 1 January 1984
    • journal article
    • research article
    • Vol. 138  (MAY) , 423-433
Abstract
The length of internodes in bovine ventral spinal nerve root fibers varies in an irregular pattern along the spinal cord with short internodes for the cervicothoracic and lumbosacral segments, and long internodes for the high cervical, thoracic and sacral segments. This pattern of variation is independent of axon caliber, which is fairly constant between roots. Internode length and fiber caliber vary independently of each other, resulting in internodes of different proportions (length/diameter quotient) for different roots. Maximum internode length was determined at .apprx. 2400 .mu.m; the longest internode found measured 2847 .mu.m. The segmental variance in ventral root internode length in the cow differs from that in man or rat, which show a craniocaudal increase in internode length. These species-dependent differences relate to differences in the degree of the developmental ascensus of the spinal cord.