Morphometry of saphenous nerve in young rats

The rat saphenous nerve contains only somato-sensory fibers and is used in investigations of neuropathic pain and its treatment. Due to its superficial anatomical path, the saphenous nerve is also widely used in electrophysiological studies. Nevertheless, morphologic and morphometric descriptions of the normal saphenous nerve are scanty in the literature and information on useful morphometric parameters of this nerve is still missing. Thus, the present study aimed to investigate the longitudinal and lateral symmetry of the saphenous nerve in young rats. Proximal and distal segments of the left and right saphenous nerves from female Wistar rats, aged 30 days (N=5) were morphometrically evaluated and comparisons were made between sides and segments. Our results show that the saphenous nerve is longitudinally and laterally symmetric since there were no morphometric differences between proximal and distal segments, as well as between right and left sides. This lateral symmetry is important in order to validate those experiments in which the contralateral nerve is used as the control. Also, the longitudinal symmetry information is fundamental to further studies involving the "dying back" neuropathy models. The present study adds to the literature new morphometric information on the rat saphenous nerve that might be useful for a better interpretation of further studies involving this nerve and experimental models of nerve diseases.

[1]  Thomas Ga.  Quantitative histology of Wallerian degeneration: II. Nuclear population in two nerves of different fibre spectrum. , 1948 .

[2]  Roland N. Auer,et al.  Automated nerve fibre size and myelin sheath measurement using microcomputer-based digital image analysis: theory, method and results , 1994, Journal of Neuroscience Methods.

[3]  H. Salgado,et al.  A descriptive and quantitative light and electron microscopy study of the aortic depressor nerve in normotensive rats. , 1997, Hypertension.

[4]  A. Blight,et al.  Morphometric analysis of experimental spinal cord injury in the cat: The relation of injury intensity to survival of myelinated axons , 1986, Neuroscience.

[5]  Fazan,et al.  Morphology of aortic depressor nerve myelinated fibers in normotensive Wistar-Kyoto and spontaneously hypertensive rats. , 1999, Journal of the autonomic nervous system.

[6]  J. Jakobsen,et al.  Neuropathy in experimental diabetes: an animal model. , 1976, British medical journal.

[7]  S. Lisney,et al.  Saphenous nerve injury and regeneration on one side of a rat suppresses the ability of the contralateral nerve to evoke plasma extravasation , 1990, Neuroscience Letters.

[8]  P. K. Thomas,et al.  Changes with age in the peripheral nerves of the rat , 2004, Acta Neuropathologica.

[9]  E. Senba,et al.  Effects of amitriptyline and gabapentin on bilateral hyperalgesia observed in an animal model of unilateral axotomy , 2005, Pain.

[10]  P R Burgess,et al.  Receptor types in cat hairy skin supplied by myelinated fibers. , 1968, Journal of neurophysiology.

[11]  P S Spencer,et al.  Peripheral Nerve Abnormalities in Aging Rats , 1979, Journal of neuropathology and experimental neurology.

[12]  V. Fazan,et al.  Streptozotocin induced diabetes as a model of phrenic nerve neuropathy in rats , 2006, Journal of Neuroscience Methods.

[13]  F. Bajrović,et al.  Sex-related difference in collateral sprouting of nociceptive axons after peripheral nerve injury in the rat , 2003, Experimental Neurology.

[14]  D. H. Kim,et al.  Labeled Schwann cell transplants versus sural nerve grafts in nerve repair. , 1994, Journal of neurosurgery.

[15]  V. Fazan,et al.  Microscopic anatomy of brachial plexus branches in Wistar rats , 2007, Anatomical record.

[16]  J. Fraher.  Myelin‐Axon relationships in the rat phrenic nerve: Longitudinal variation and lateral asymmetry , 1992, The Journal of comparative neurology.

[17]  Valéria Paula Sassoli Fazan,et al.  Peripheral nerve morphometry: Comparison between manual and semi-automated methods in the analysis of a small nerve , 2007, Journal of Neuroscience Methods.

[18]  C Messina,et al.  A computer‐assisted automatic method for myelinated nerve fiber morphometry , 1992, Acta neurologica Scandinavica.

[19]  A. Takahashi,et al.  Morphometric analysis of the sural nerve in experimental dorsal rhizotomy in rats , 1993, Journal of the Neurological Sciences.

[20]  A. Brenan,et al.  The demonstration of the cutaneous distribution of saphenous nerve C-fibres using a plasma extravasation technique in the normal rat and following nerve injury. , 1988, Journal of anatomy.

[21]  W. Rushton.  A theory of the effects of fibre size in medullated nerve , 1951, The Journal of physiology.

[22]  H. H. Donaldson,et al.  On the areas of the axis cylinder and medullary sheath as seen in cross sections of the spinal nerves of vertebrates , 1905 .

[23]  R. S. Smith,et al.  Myelinated nerve fibers: computed effect of myelin thickness on conduction velocity. , 1970, The American journal of physiology.

[24]  E. McLachlan,et al.  Selective Reactions of Cutaneous and Muscle Afferent Neurons to Peripheral Nerve Transection in Rats , 2003, The Journal of Neuroscience.

[25]  E. Kokmen,et al.  Morphometric Alteration of Rat Myelinated Fibers with Aging , 1989, Journal of neuropathology and experimental neurology.

[26]  A. Matsumoto,et al.  Number and diameter distribution of myelinated afferent fibers innervating the paws of the cat and monkey , 1975, Experimental Neurology.

[27]  André Jeronimo,et al.  Microscopic anatomy of the sural nerve in the postnatal developing rat: a longitudinal and lateral symmetry study , 2005, Journal of anatomy.

[28]  B. Lynn.  Effect of neonatal treatment with capsaicin on the numbers and properties of cutaneous afferent units from the hairy skin of the rat , 1984, Brain Research.

[29]  J. Ochoa,et al.  The normal sural nerve in man. I. Ultrastructure and numbers of fibres and cells. , 1969, Acta neuropathologica.

[30]  J. Unger,et al.  Nerve Growth Factor (NGF) and Diabetic Neuropathy in the Rat: Morphological Investigations of the Sural Nerve, Dorsal Root Ganglion, and Spinal Cord , 1998, Experimental Neurology.

[31]  F. Leblond,et al.  Behavioral, pharmacological and molecular characterization of the saphenous nerve partial ligation: A new model of neuropathic pain , 2005, Neuroscience.

[32]  S. Lisney,et al.  The numbers of unmyelinated and myelinated axons in normal and regenerated rat saphenous nerves , 1987, Journal of the Neurological Sciences.

[33]  Z. Wiesenfeld‐Hallin,et al.  Expansion of innervation territory by afferents involved in plasma extravasation after nerve regeneration in adult and neonatal rats , 2004, Experimental Brain Research.

[34]  D. Ceballos,et al.  Morphometric and ultrastructural changes with ageing in mouse peripheral nerve , 1999, Journal of anatomy.