Summary
A morphometric study was performed on sural nerves from human fetuses at 15 to 36 weeks postovulation. There were no myelinated fibres at 15 and 16 weeks, but by 21 weeks there were 5,000/mm2, rising to 25,000/mm2 at 36 weeks. During the fetal period, the mean myelin lamellar count trebled and the g ratio (axon diameter: total fibre diameter) decreased from 0.90 to 0.75, although the axon diameter of myelinated fibres did not increase. The smallest myelinated axon diameter was 0.63 μm, whereas the largest unmyelinated axon in a 1:1 relationship with a Schwann cell was 2.83 μm, suggesting that axon size is unlikely to be the only stimulus for myelination. The density of unmyelinated axons that were the sole occupants of a Schwann cell fell considerably between 23 and 33 weeks, while the ratio of total unmyelinated axons to myelinated fibres decreased from 82:1 at 21 weeks to 6:1 at 36 weeks. Data for Schwann cell nuclear density and percentages of fibres cut through the nucleus are also presented.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Behse F, Buchthal F, Carlsen F, Knappeis GG (1972) Hereditary neuropathy with liability to pressure palsies. Brain 95:777–794
Behse F, Buchthal F, Carlsen FM, Knappeis GG (1975) Unmyelinated fibres and Schwann cells of sural nerve in neuropathy. Brain 98:493–510
Cravioto H (1965) The role of Schwann cells in the development of human peripheral nerves. An electron microscope study. J Ultrastruct Res 12:634–651
Davison AN, Duckett S, Oxbury JM (1973) Correlative morphological and biochemical studies of the human fetal sciatic nerve. Brain Res 58:327–342
Dunn JS (1970) Developing myelin in human peripheral nerve. Scott Med J 15:108–117
Dyck PJ (1966) Histological measurements and fine structure of biopsied sural nerve: normal, and in peroneal muscular atrophy, hypertrophic neuropathy and congenital sensory neuropathy. Mayo Clin Proc 41:742–774
Dyck PJ, Gomez MR (1968) Segmental demyelination in Dejerine-Sottas disease: light, phase-contrast, and electron microscopic studies. Mayo Clin Proc 43:280–296
Dyck PJ, Gutrecht JA, Bastron JA, Karnes WE, Dale AJD (1968) Histologic and teased-fiber measurements of sural nerve in disorders of lower motor and primary sensory neurons. Mayo Clin Proc 43:81–123
Dyck PJ, Lambert EH, Sanders K, O'Brien PC (1971) Severe hypomyelination and marked abnormality of conduction in Dejerine-Sottas hypertrophic neuropathy: myelin thickness and compound action potential of sural nerve in vitro. Mayo Clin Proc 46:432–436
Eames RA, Gamble HJ (1970) Schwann cell relationships in normal human cutaneous nerve. J Anat 106:417–435
Friede RL, Beuche W (1985) Combined scatter diagrams of sheath thickness and fibre calibre in human sural nerves: changes with age and neuropathy. J Neurol Neurosurg Psychiatry 48:749–756
Friede RL, Bischhausen S (1982) How are sheath dimensions affected by axon caliber and internode length? Brain Res 235:335–350
Friede AL, Samorajski T (1967) Relation between the number of myelin lamellae and axon circumference in fibers of vagus and sciatic nerves. J Comp Neurol 130:223–232
Friede AL, Samorajski T (1968) Myelin formation in the sciatic nerve of the rat. A quantitative electron microscopic histochemical and radioautographic study. J Neuropathol Exp Neurol 27:546–570
Gamble HJ (1966) Further electron microscope studies of human foetal peripheral nerves. J Anat 100:487–502
Gamble HJ, Breathnach AS (1965) An electron-microscope study of human foetal peripheral nerves. J Anat 99:573–584
Geren BB (1954) The formation from the Schwann cell surface of myelin in the peripheral nerves of chick embryos. Exp Cell Res 7:558–562
Gutrecht JA, Dyck PJ (1970) Quantitative teased-fiber and histologic studies of human sural nerve during postnatal development. J Comp Neurol 138:117–130
Jacobs JM, Love S (1985) Qualitative and quantitative morphology of human sural nerve at different ages. Brain (in press)
Ochoa J (1971) The sural nerve of the human foetus: electron microscopic observations and counts of axons. J Anat 108:231–245
Ochoa J, Mair WGP (1969a) The normal sural nerve in man. I. Ultrastructure and numbers of fibres and cells. Acta Neuropathol (Berl) 13:197–216
Ochoa J, Mair WGP (1969b) The normal sural nerve in man. II. Changes in the axons and Schwann cells during ageing. Acta Neuropathol (Berl) 13:217–239
Origuchi Y (1981) Quantitative histological study in the sural nerves of children. Brain Dev 3:395–402
O'Sullivan DJ, Swallow M (1968) The fibre size and content of the radial and sural nerves. J Neurol Neurosurg Psychiatry 31:464–470
Schmitt FO, Bear RS (1937) Optical properties of the axon sheaths of crustacean nerves. J Cell Comp Physiol 9:261–275
Schröder JM, Bohl J, Brodda K (1978) Changes of the ratio between myelin thickness and axon diameter in the human developing sural nerve. Acta Neuropathol (Berl) 43:169–178
Sharma AK, Thomas PK (1975) Quantitative studies on age changes in unmyelinated fibres in the vagus nerve of man. In: Kunze K, Desmedt JE (eds) Studies on neuromuscular diseases. Karger, Basel, pp 211–219
Sievers J (1971) Basic two-dye stains for epoxy-embedded 0.3–1 μ sections. Stain Technol 46:195–199
Streeter GL (1920) Weight, sitting height, head size, foot lengt, and menstrual age of the human embryo. Contrib Embryol (Carnegie Inst Wash) 11:143–170
Thomas PK, Ochoa J (1984) Microscopic anatomy of peripheral nerve fibers. In: Dyck PJ, Thomas PK, Lambert EH, Bunge R (eds) Peripheral neuropathy, 2nd edn. Saunders, Philadelphia, pp 39–96
Tohgi HH, Tsukagoshi H, Toyokura Y (1977) Quantitative changes with age in normal sural nerves. Acta Neuropathol (Berl) 38:213–220
Weller RO (1967) An electron microscopic study of hypertrophic neuropathy of Dejerine and Sottas. J Neurol Neurosurg Psychiatry 30:111–125
Wozniak W, O'Rahilly R (1981) Fine structure and myelination of the developing human vagus nerve. Acta Anat (Basel) 109:218–230
Wozniak W, O'Rahilly R, Bruska M (1982) Myelination of the human fetal phrenic nerve. Acta Anat (Basel) 112:281–296
Author information
Authors and Affiliations
Additional information
Supported by the Friedreich's Ataxia Group, and by grants from Ciba-Geigy Ltd., Basel and the London University Central Equipment Fund for the purchase of image analysis equipment
Rights and permissions
About this article
Cite this article
Shield, L.K., King, R.H.M. & Thomas, P.K. A morphometric study of human fetal sural nerve. Acta Neuropathol 70, 60–70 (1986). https://doi.org/10.1007/BF00689515
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00689515