Altered ratio between axon diameter and myelin sheath thickness in regenerated nerve fibers

Jm, Schröder

doi:10.1016/0006-8993(72)90215-6

Cited by 180 publications

(74 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The relationship between the axon and the myelin sheath has been generally observed in normal nerve fibers (Gutrecht and Dyck, 1970;Schröder, 1972;Sananpanich et al, 2002). In this study, no difference in the relationship was recognized with increasing age or between the segments.…”

Section: Discussionsupporting

confidence: 43%

Microscopic anatomy of brachial plexus branches in Wistar rats

Santos

Suaid

Fazan

et al. 2007

The Anatomical Record

View full text Add to dashboard Cite

In the present study, we analyze the morphology and morphometry of the lateral proper digital nerve of the third finger, and of the proximal and distal segments of the ulnar, median, and radial nerves, in Wistar rats 4 or 7 weeks old. The fascicular area and diameter were generally significantly greater in the proximal compared to distal segments and tended to be larger in 7-week-old compared to 4-week-old rats (e.g., median nerve area of 0.13 mm 2 for the proximal and 0.07 mm 2 for distal segments in 4-weekold rats, and 0.17 and 0.10 mm 2 , respectively, for the proximal and distal segments of 7-week-old rats). The number of fascicles was significantly greater while the number of myelinated fibers was significantly less in the distal segments (e.g., 1,359 and 509 myelinated fibers, respectively, in the proximal and distal segments of the radial nerve 4-week-old rats). There was no significant difference in these parameters between the two age groups. The diameter of the myelinated fibers and their respective axons increased from 4 to 7 weeks of age (e.g., myelinated fiber diameter of 4.10 mm in 4-week-old animals and 4.7 mm in the ulnar nerve proximal segment of 7-week-old rats). The g-ratio regression line (axon diameter vs. fiber diameter quotient) was outlined for all the nerves studied here. Differences in myelinated fiber density were detected between the segments of the radial nerve, accompanying the number of myelinated fibers. Detailed knowledge of the microscopic anatomy of rat forelimb nerves provides control data for comparison with studies of experimentally induced neuropathies, which can shed more light on human neuropathies. Anat Rec, 290:477-485, 2007. 2007 Wiley-Liss, Inc.

show abstract

Section: Discussionsupporting

confidence: 43%

Microscopic anatomy of brachial plexus branches in Wistar rats

Santos

Suaid

Fazan

et al. 2007

The Anatomical Record

View full text Add to dashboard Cite

show abstract

“…Diversos estudos constataram a dificuldade de regeneração nervosa após uma axotomia periférica, com diminuição do diâmetro da fibra regenerada, formação de uma bainha de mielina mais fina, e conseqüente diminuição da velocidade de condução 6,7 .…”

Section: Discussionunclassified

Uso da celulose liofilizada em lesões de nervos periféricos com perda de substância

Mello

Feltrin

Selbach

et al. 2001

Arq. Neuro-Psiquiatr.

View full text Add to dashboard Cite

RESUMO -O trabalho analisou a celulose liofilizada como invólucro de lesões de nervos periféricos, com perda de substância, investigando a intensidade de reação inflamatória e o alinhamento axonal. Dez cães foram divididos em 3 grupos: Grupo 1 -seccção e recolocação de 1 cm de nervo ciático; Grupo 2 -não recolocado fragmento seccionado; Grupo 3 -sutura epineural, sem invólucro celulósico. A recuperação motora iniciou na oitava semana, lenta e progressiva, sem recuperação total. A autópsia mostrou reação fibrótica ao redor da celulose e aderência ao plano muscular. Quando o enxerto foi recolocado, constatou-se continuidade do nervo com aumento de calibre local. Nos dez cães foi observada fibrose e regeneração neural variáveis na área de secção do nervo. Os grupos 1 e 3 mostraram coaptação entre cotos e enxerto. Concluiu-se que a celulose liofilizada provocou moderada reação fibrótica com realinhamento e crescimento axonal quando foi recolocado, como enxerto, o fragmento do nervo seccionado.PALAVRAS-CHAVE: nervo periférico, trauma, celulose. Use of lyophilized cellulose in peripheral nerve lesions with loss of substanceABSTRACT -Lyophilized cellulose was analysed to verify the degree of inflamatory reaction and axon realignement in the sciatic nerve after loss of neural substance. Ten mongrel dogs were divided into: Group 1 -1 cm section of sciatic nerve which was replaced at lesion site; Group 2 nerve section without fragment replacement. The section site was involved with lyophilized cellulose. Group 3 -1 cm fragment section sutured epineurally. Motor response started at eighth week. Moderate fibrotic reaction to cellulose was seen in Group 1 and 2 animals. Groups 1 and 3 showed coaptation between the nerve and nerve graft with ongoing axons. In Group 2, 1 dog showed regrouth of axons through the empty space. It was concluded that lyophilized cellulose caused moderate fibrous reaction when implanted in peripheral nerve lesions with loss of substance; it can act as envellop protection in those lesions mainly if a neural graft is inserted.

show abstract

“…The distal myelinated and unmyelinated axons after 3 months were still thinner than pormal, as were the newly formed myelin sheaths3s8.' 1,13,14720731, 38 (Figs. 6-8, Table 2).…”

Section: Prnmentioning

confidence: 97%

Axonal branching following crush lesions of peripheral nerves of rat

1988

View full text Add to dashboard Cite

Branching of myelinated and unmyelinated nerve fibers in normal and regenerating personal and soleus nerves was studied by light and electron microscopy. There were at most 2% more myelinated and 13% more unmyelinated axons in the distal as compared with the proximal nerve segments. Two to four weeks after a crush lesion the distal axons became 2-3 times more numerous; thereafter their number decreased. The number of axons in the proximal nerve segment did not change. The number of myelinated sprouts in most regenerated nerves equalled the number of myelinated fibers in the proximal nerve, while the number of unmyelinated axons after 12-19 weeks was 18-60% higher than normal. Branching was not restricted to the crush region. The results indicate that following a crush lesion all axons branch but only branches of unmyelinated fibers persist for a prolonged period of time. It is tentatively suggested that regenerating axons branch when searching for a target and that when contact is made with the target this prevents additional branching and eliminates redundant branches. Myelinated axons are guided by existing Schwann cells, whereas unmyelinated axons do not follow predetermined pathways; this may explain their greater tendency to form permanent branches.

show abstract

Altered ratio between axon diameter and myelin sheath thickness in regenerated nerve fibers

Cited by 180 publications

References 18 publications

Microscopic anatomy of brachial plexus branches in Wistar rats

Microscopic anatomy of brachial plexus branches in Wistar rats

Uso da celulose liofilizada em lesões de nervos periféricos com perda de substância

Axonal branching following crush lesions of peripheral nerves of rat

Contact Info

Product

Resources

About