Abstract
Myelinated nerve fibers suffer from different degrees of atrophy with age. The success of subsequent regeneration varies. The aim of this research was to analyze myelinated fibers of the human sciatic nerve during the aging process. Morphometric analysis was performed on 17 cases with an age range from 9 to 93 years. The outer and inner diameter of 100 randomly selected nerve fibers was measured in each of the cases evaluated, and the g-ratio (axonal diameter/outer diameter of the whole nerve fiber) of each was calculated. Scatter plots of the diameters and g-ratios of the analyzed fibers were then analyzed. Nerve fibers of each case were classified into three groups according to the g-ratio values: group I (g-ratio lower than 0.6), group II (g-ratio from 0.6 to 0.7) and group III (g-ratio higher than 0.7). Afterwards, nerve fibers of group II were further classified into small and large subgroups. The percentages of each group of nerve fibers were computed for each case and these values were used for correlational and bivariate linear regression analysis. The percentage of myelinated nerve fibers with large diameter and optimal g-ratio of the sciatic nerve declines significantly with age. This is accompanied by a simultaneous significant increase in the percentage of small myelinated fibers with g-ratio values close to 1 that occupy the upper left quadrant of the scatter plot. It can be concluded that aging of the sciatic nerve is associated with significant atrophy of large myelinated fibers. Additionally, a significant increase in regenerated nerve fibers with thinner myelin sheath is observed with age, which, together with the large myelinated fiber atrophy, might be the cause of the age-related decline in conduction velocity. A better understanding of the changes in aging peripheral nerves might improve interpretation of their pathological changes, as well as comprehension of their regeneration in individuals of different age.
Similar content being viewed by others
References
Asbury AK, Johnson PC (1978) Pathology of peripheral nerve. Saunders, Philadelphia
Atkinson CJ, Santer RM (1999) Quantitative studies on myelinated and unmyelinated nerve fibers in the interatrial septal region of aged rat hearts. J Auton Nerv Syst 77:172–176
Azcoitia I, Leonelli E, Magnaghi V, Veiga S, Garcia-Segura LM, Melcangi RC (2003) Progesterone and its derivatives dihydroprogesterone and tetrahydroprogesterone reduce myelin fiber morphological abnormalities and myelin fiber loss in the sciatic nerve of aged rats. Neurobiol Aging 24:853–860
Bosboom WM, van den Berg LH, Franssen H et al (2001) Diagnostic value of sural nerve demyelination in chronic inflammatory demyelinating polyneuropathy. Brain 124(Pt 12):2427–2438
Ceballos D, Cuadras J, Verdu E, Navarro X (1999) Morphometric and ultrastructural changes with ageing in mouse peripheral nerve. J Anat 195:563–576
Chentanez V, Agthong S, Huanmanop T, Pairoh S, Kaewsema A (2010) Morphometric analysis of the human superficial radial nerve. Anat Sci Int 85(3):167–170
Chomiak T, Hu B (2009). What is the optimal value of the g-ratio for myelinated fibers in the rat CNS? A theoretical approach. PLoS One 13;4(11):e7754
Drury RAB, Wallington EA (1980) Carleton’s histological technique, 5th edn. Oxford University Press, New York, pp 143–144
Fahrenkamp I, Friede RL (1987) Characteristic variations of relative myelin sheath thickness in 11 nerves of the rat. Anat Embryol 177:115–121
Friede RL, Beuche W (1985) Combined scatter diagrams of sheath thickness and fibr ecalibre in human sural nerves: changes with age and neuropathy. J Neurol Neurosurg Psychiat 48:749–756
Jacobs JM, Love S (1985) Qualitative and quantitative morphology of human sural nerve at different ages. Brain 108:897–924
Jeronimo A, Jeronimo CA, Rodrigues Filho OA, Sanada LS, Fazan VP (2008) A morphometric study on the longitudinal and lateral symmetry of the sural nerve in mature and aging female rats. Brain Res 1222:51–60
Johansson CS, Stenström M, Hildebrand C (1996) Target influence on aging of myelinated sensory nerve fibers. Neurob Aging 17:61–66
Kovačić U, Bajrović FF (2009) Chapter 26: age-related differences in the reinnervation after peripheral nerve injury. Int Rev Neurobiol 87:465–482
Malik RA, Veves A, Walker D et al (2001) Sural nerve fibre pathology in diabetic patients with mild neuropathy: relationship to pain, quantitative sensory testing and peripheral nerve electrophysiology. Acta Neuropathol 101:367–374
Melcangi RC, Magnaghi V, Martini L (2000) Aging in peripheral nerves: regulation of myelin proteingenes by steroid hormones. Prog Neurobiol 60:291–308
Muratori L, Ronchi G, Raimondo S, Giacobini-Robecchi MG, Fornaro M, Geuna S (2012) Can regenerated nerve fibers return to normal size? A long-term post-traumatic study of the rat median nerve crush injury model. Microsurgery 32(5):383–387
O`Sallivan DJ, Swallow M (1968) The fibre size and content of the radial and sural nerves. J Neurol Neurosurg Psychiatry 31:464–470
Peters A (2002) The efects of normal aging on myelin and nerve fibers: a review. J Neurocytol 31:581–593
Rushton WA (1951) A theory of the effects of fibre size in medullated nerve. J Physiol 115(1):101–122
Sanada LS, da Rocha Kalil AL, Tavares MR, Neubern MC, Salgado HC, Fazan VP (2012) Sural nerve involvement in experimental hypertension: morphology and morphometry in male and female normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). BMC Neurosci. 2:13–24
Soltanpour N, AsghariVostacolaee Y, Pourghasem M (2012) Comparison of morphometric aspects of light and electron microscopy of the hypoglossal nerve between young and aged male wistar rats. Cell J 13(4):229–236
Thomas PK, Ochoa J (1984) Microscopic anatomy of the peripheral nervous system. In: Dyck PJ, Thomas PK (eds) Peripheral neurophathy, 2nd edn. Saunders, London, pp 39–91
Tohgi H, Tsukagaoshi H, Toyokura Y (1977) Quantitative changes with age in normal sural nerves. Acta Neuropathol 38:213–220
Verdu E, Ceballos D, Vilches JJ, Navarro X (2000) Influence of aging on peripheral nerve function and regeneration. J Peripher Nerv Syst 5:191–208
Acknowledgment
Contract grant sponsor: Ministry of Science and Technological Development of Republic of Serbia; contract grant number: 175092.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Ugrenović, S., Jovanović, I., Vasović, L. et al. Morphometric analysis of the diameter and g-ratio of the myelinated nerve fibers of the human sciatic nerve during the aging process. Anat Sci Int 91, 238–245 (2016). https://doi.org/10.1007/s12565-015-0287-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12565-015-0287-9