scholarly journals THE GEOMETRY OF PERIPHERAL MYELIN SHEATHS DURING THEIR FORMATION AND GROWTH IN RAT SCIATIC NERVES

1971 ◽  
Vol 48 (2) ◽  
pp. 348-367 ◽  
Author(s):  
Henry deF. Webster
Keyword(s):  
Growth Rate ◽  
Schwann Cell ◽  
Cell Surface ◽  
Transverse Plane ◽  
Electron Micrograph ◽  
Myelin Sheaths ◽  
Sciatic Nerves ◽  
Length And Area ◽  
Different Levels ◽  
Small Bundle

In rat sciatic nerves, a small bundle of fibers was identified in which myelin sheaths were absent at birth, appeared within 3 days, and grew rapidly for 2 wk. During this interval, nerves were removed from littermates and were sectioned serially in the transverse plane. Alternating sets of thin and thick sections were used to prepare electron micrograph montages in which single myelinating axons could be identified and traced distally. During the formation of the first spiral turn, the mesaxon's length and configuration varied when it was studied at different levels in the same Schwann cell. The position of the mesaxon's termination shifted while its origin, at the Schwann cell surface, remained relatively constant. Along myelin internodes composed of two to six spiral turns, there were many variations in the number of lamellae and their contour. Near the mesaxon's origin, longitudinal strips of cytoplasm separated the myelin layers. Thicker sheaths were larger in circumference, more circular in transverse sections, and more uniform at different levels. Irregularities were confined to the paranodal region, and separation of lamellae by cytoplasm occurred at Schmidt-Lantermann clefts. Approximate dimensions of the bundle, its largest fibers, and their myelin sheaths were measured and calculated. The myelin membrane's transverse length and area increased exponentially with time; the growth rate increased rapidly during the formation of the first four to six spiral layers and remained relatively constant during the subsequent enlargement of the compact sheath.

scholarly journals ELECTRON MICROSCOPE STUDIES OF THE FORMATION OF NODES OF RANVIER IN MOUSE SCIATIC NERVES

1957 ◽  
Vol 3 (4) ◽  
pp. 589-598 ◽  
Author(s):  
Betty Geren Uzman ◽  
Genevieve Nogueira-Graf
Keyword(s):  
Electron Microscope ◽  
Schwann Cell ◽  
Cell Surface ◽  
Myelin Sheath ◽  
Three Dimensions ◽  
Nodes Of Ranvier ◽  
Internodal Length ◽  
Intimate Contact ◽  
General Picture ◽  
Sciatic Nerves

Observations with the electron microscope of longitudinal sections of the sciatic nerves of infant mice during the period of early myelin formation are described. These observations are interpreted in relation to previous studies of transverse sections, and a general picture of the formation of an internodal length of the myelin sheath in three dimensions is formulated. In general, an internodal length of myelin sheath is attained by the spiral wrapping of the infolded Schwann cell surface; the increase in length of the internode during maturation is at least partially explained by the increased length of axon covered by the overlapping of successive layers during the wrapping of the infolded Schwann cell surface; and the nodes of Ranvier refer to the structure complex at the junctions of adjacent non-syncytial Schwann cells. The fact that the mode of formation of myelin brings each of its layers into intimate contact with the axon surface at the nodes is emphasized because of the possible functional significance of this arrangement. The manner of origin of Schmidt-Lantermann clefts remains obscure. Certain isolated observations provide evidence for the possibility that occasional internodes of myelin may form from several small segments of myelin within a single Schwann cell.

Incorporation of Cholesterol into Peripheral Nerve Myelin

1972 ◽  
Vol 30 ◽  
pp. 334-335
Author(s):  
Frank A. Rawlins
Keyword(s):  
Electron Microscope ◽  
Sciatic Nerve ◽  
Electron Microscope Autoradiography ◽  
Myelin Sheaths ◽  
Microscope Autoradiography ◽  
Grain Distribution ◽  
Sciatic Nerves ◽  
Autoradiographic Analysis ◽  
Old Mice ◽  
Short Times

Several speculations exist as to the site of incorporation of preformed molecules into myelin. The possibility that an autoradiographic analysis of cholesterol-1,2-H3 incorporation at very short times after injection might shed some light in the solution of that problem led to the present experiment.Cholesterol-1,2-H3 was injected intraperitoneally into 24 tenday old mice. The animals were then sacrificed at 10,20,30,40,60,90,120 and 180 min after the injection and the sciatic nerves were processed for electron microscope autoradiography. To analyze the grain distribution in the autoradiograms of cross and longitudinal sections from each sciatic nerve myelin sheaths were subdivided into three compartments named: outer 1/3, middle 1/3 and inner 1/3 compartments.It was found that twenty min. after the injection of cholesterol -1.2-H3 (Figs. 1 and 2), 55% of the total number of grains (t.n.g) found in myelin were within the outer 1/3 compartment, 9% were within the middle 1/3 and 36% within the inner 1/3 compartment

scholarly journals Chitosan Micro-Grooved Membranes with Increased Asymmetry for the Improvement of the Schwann Cell Response in Nerve Regeneration

2021 ◽  
Vol 22 (15) ◽  
pp. 7901
Author(s):  
Luca Scaccini ◽  
Roberta Mezzena ◽  
Alessia De Masi ◽  
Mariacristina Gagliardi ◽  
Giovanna Gambarotta ◽  
...  
Keyword(s):  
Schwann Cell ◽  
Nerve Regeneration ◽  
High Fidelity ◽  
Solvent Casting ◽  
Peripheral Nerve Injuries ◽  
Cell Shaping ◽  
Micro Pattern ◽  
Chitosan Scaffolds ◽  
Set Up ◽  
Different Levels

Peripheral nerve injuries are a common condition in which a nerve is damaged, affecting more than one million people every year. There are still no efficient therapeutic treatments for these injuries. Artificial scaffolds can offer new opportunities for nerve regeneration applications; in this framework, chitosan is emerging as a promising biomaterial. Here, we set up a simple and effective method for the production of micro-structured chitosan films by solvent casting, with high fidelity in the micro-pattern reproducibility. Three types of chitosan directional micro-grooved patterns, presenting different levels of symmetricity, were developed for application in nerve regenerative medicine: gratings (GR), isosceles triangles (ISO) and scalene triangles (SCA). The directional patterns were tested with a Schwann cell line. The most asymmetric topography (SCA), although it polarized the cell shaping less efficiently, promoted higher cell proliferation and a faster cell migration, both individually and collectively, with a higher directional persistence of motion. Overall, the use of micro-structured asymmetrical directional topographies may be exploited to enhance the nerve regeneration process mediated by chitosan scaffolds.

Neonatal stem cells exhibit specific characteristics in function, proliferation, and cellular signaling that distinguish them from their adult counterparts

2008 ◽  
Vol 294 (5) ◽  
pp. R1491-R1497 ◽  
Author(s):  
Troy A. Markel ◽  
Meijing Wang ◽  
Paul R. Crisostomo ◽  
Maiuxi C. Manukyan ◽  
Jeffrey A. Poynter ◽  
...  
Keyword(s):  
Stem Cells ◽  
Cell Surface ◽  
Surface Markers ◽  
Cell Surface Markers ◽  
Local Inflammatory Response ◽  
Cell Counts ◽  
Marrow Mesenchymal Stem Cells ◽  
Growth Factor Production ◽  
Erk Inhibition ◽  
Different Levels

Stem cells may be a novel treatment modality for organ ischemia, possibly through beneficial paracrine mechanisms. Stem cells from older hosts have been shown to exhibit decreased function during stress. We therefore hypothesized that 1) neonatal bone marrow mesenchymal stem cells (nBMSCs) would produce different levels of IL-6, VEGF, and IGF-1 compared with adults (aBMSCs) when stimulated with TNF or LPS; 2) differences in cytokines would be due to distinct cellular characteristics, such as proliferation or pluripotent potential; and 3) differences in cytokines would be associated with differences in p38 MAPK and ERK signaling within nBMSCs. BMSCs were isolated from adult and neonatal mice. Cells were exposed to TNF or LPS with or without p38 or ERK inhibition. Growth factors were measured via ELISA, proliferation via daily cell counts, cell surface markers via flow cytometry, and pluripotent potential via alkaline phosphatase activity. nBMSCs produced lower levels of IL-6 and VEGF, but higher levels of IGF-1 under basal conditions, as well as after stimulation with TNF, but not LPS. Neonatal and adult BMSCs had similar pluripotent potentials and cell surface markers, but nBMSCs proliferated faster. Furthermore, p38 and ERK appeared to play a more substantial role in nBMSC cytokine and growth factor production. Neonatal stem cells may aid in decreasing the local inflammatory response during ischemia, and could possibly be expanded more rapidly than adult cells prior to therapeutic use.

scholarly journals THE EFFECTS OF FEED ON THE INTAKE, DIGESTIBILITY AND GROWTH RATE OF WEST AFRICAN DWARF GOATS FED GLIRICIDIA sepium AND LEUCAENA LEUCOCOEPHALA

2021 ◽  
Vol 22 (2) ◽  
pp. 164-168
Author(s):  
S. M. Odeyinka ◽  
A. A. Ademosun
Keyword(s):  
Growth Rate ◽  
Dry Matter ◽  
Gliricidia Sepium ◽  
West African ◽  
Dry Matter Intake ◽  
West African Dwarf ◽  
West African Dwarf Goats ◽  
Significant Difference ◽  
Different Levels ◽  
Dwarf Goats

The study evaluated the effects of level of feed offer on dry matter intake (DMI) , digestibility, the parts of plants selected and on the growth rate of West African dwarf (WAD) goats without resulting in toxicity. Seven different levels of feed offer ranging from 40g/kg0.75/day to 130Wkg0.75/day in increments of 15g/kg0.75) were fed to two groups of goats. The first group was fed 100% Gliricidia while the while the second was fed 50% Gliricidia and 50% Leucaena diet (50/50). The level of feed offer had significant effect on the DIM and digestible DMI (DDMI) of the goat (P < 0.01). The Leucaena intake in a 50/50 diet was always higher than the Gliricidia intake except at 55g1kg0.75 offer level. The level of feed offer had significant effects on the parts of plants selected (P < 0.01.) and on the growth rate. The leaf intake was statistically higher than the stem intake (P < 0.01). All the goats on 40g/kg0.75 and 55g/kg0.75 on a 100% Gliricidia diet lost weight while only those on 40g/kg0.75 lost weight on a 50/50 diet. There was no significant difference in the growth rate of goats on feed offer levels of 70g to 130g/kg0.75 (P > 0.05). The study indicate that goats performance was higher on a mixed browse diet than on Gliricidia alone. Goats performed best at 100g/kg0.75 offer level.

scholarly journals Remyelination in experimentally demyelinated connexin 32 KnockOut mice

2009 ◽  
Vol 67 (2b) ◽  
pp. 488-493
Author(s):  
Adriano Tony Ramos ◽  
Paulo César Maiorka ◽  
Maria Lúcia Zaidan Dagli ◽  
Fernando Yutaka Moniwa Hosomi ◽  
Kalan Bastos Violin ◽  
...  
Keyword(s):  
Knockout Mice ◽  
Connexin 32 ◽  
Ethidium Bromide Solution ◽  
Normal Pattern ◽  
Myelin Sheaths ◽  
Transmission Electron ◽  
Bromide Solution ◽  
Sciatic Nerves ◽  
Electron Microscopical

The aim of this study was to evaluate the role of connexin 32 (Cx 32) during remyelination of the peripheral nervous system, through a local injection of either 0,1% ethidium bromide solution or saline in the sciatic nerve of Cx 32 knockout mice. Euthanasia was performed ranging from 1, 2, 3, 7, 15, 21 to 30 days after injection. Histochemical, immunohistochemical, immunofluorescence and transmission electron microscopical techniques were used to analyze the development of the lesions. Within the sciatic nerves, Schwann cells initially showed signs of intoxication and rejected their sheaths; after seven days, some thin newly formed myelin sheaths with uneven compactness and redundant loops (tomacula) were conspicuous. We concluded that the regeneration of lost myelin sheaths within the PNS followed the pattern already reported for this model in other laboratory species. Therefore, these results suggest that absence of Cx 32 did not interfere with the normal pattern of remyelination in this model in young mice.

scholarly journals Polarization of myelinating Schwann cell surface membranes: role of microtubules and the trans-Golgi network

1995 ◽  
Vol 15 (3) ◽  
pp. 1797-1807 ◽  
Author(s):  
BD Trapp ◽  
GJ Kidd ◽  
P Hauer ◽  
E Mulrenin ◽  
CA Haney ◽  
...  
Keyword(s):  
Schwann Cell ◽  
Cell Surface ◽  
Trans Golgi Network ◽  
Myelinating Schwann Cell ◽  
Golgi Network

From transcription to cell surface expression, the induction of MHC class II I-Aα by interferon-γ in macrophages is regulated at different levels

2001 ◽  
Vol 53 (2) ◽  
pp. 136-144 ◽  
Author(s):  
Martin Cullell-Young ◽  
Marta Barrachina ◽  
Carlos López-López ◽  
Eduard Goñalons ◽  
Jorge Lloberas ◽  
...  
Keyword(s):  
Cell Surface ◽  
Mhc Class Ii ◽  
Surface Expression ◽  
Class Ii ◽  
Interferon Γ ◽  
Cell Surface Expression ◽  
Different Levels

An analysis of growth of different cattle genotypes reared in different environments

1984 ◽  
Vol 103 (1) ◽  
pp. 137-153 ◽  
Author(s):  
J. E. Frisch ◽  
T. E. Vercoe
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
High Growth ◽  
Environmental Stresses ◽  
Growth Potential ◽  
Gastrointestinal Helminths ◽  
Treatment Groups ◽  
Survival And Growth ◽  
Different Levels ◽  
High Growth Potential

SummaryCalves from three breeds, Brahman, Hereford × Shorthorn (HS) and Brahman × HS (BX), were divided equally into two groups, one of which was treated every 3 weeks from birth onwards to control ticks and gastrointestinal helminths, and one of which was untreated. Mortalities, growth rates and levels of resistance to environmental stresses that affected both mortality and growth under grazing conditions were recorded for all animals up to weaning (6 months) and for all males up to 15 months of age. The Brahmans were the most and the HS were the least resistant to environmental stresses, each of which was shown to depress growth in proportion to its magnitude and to contribute to the high mortalities of the HS. All breeds responded positively to parasite control with the greatest response in both survival and growth in the HS breed and the least response in the Brahman breed.Samples of males from the various breed-treatment groups were taken into pens where they were protected from environmental stresses and fed both low-quality pasture hay and high-quality lucerne hay ad libitum. Measurements were made of fasting metabolism, maintenance requirement, voluntary food intake and gain, variables related to the growth potential of each animal. The HS animals had the highest whilst the Brahmans had the lowest values for each variable.However, despite their low growth potential, the Brahmans had the highest growtli rate, and the HS, despite their high growth potential, had the lowest growth rate, when growth was measured in the presence of all environmental stresses. When parasites were controlled, growth rates were highest for the BX, the breed with intermediate growtli potential, and did not differ between the HS and Brahmans. These interactions arose because of the different contributions of resistance to environmental stresses and growth potential to growth rate measured at the different levels of environmental stresses. The relevance of these interactions to breed evaluation and cross-breeding is considered.Growth potential and resistance to environmental stresses were negatively correlated both between and within breeds, though the latter was biased by the effects of compensation. The influence of these relationships on the likely outcome of selection for increased growth rate, both between and within breeds, is discussed.

Immune attack on the schwann cell surface in acute inflammatory demyelinating polyneuropathy

1996 ◽  
Vol 39 (5) ◽  
pp. 625-635 ◽  
Author(s):  
C. E. Hafer-Macko ◽  
K. A. Sheikh ◽  
C. Y. Li ◽  
T. W. Ho ◽  
D. R. Cornblath ◽  
...  
Keyword(s):  
Schwann Cell ◽  
Cell Surface ◽  
Demyelinating Polyneuropathy ◽  
Acute Inflammatory Demyelinating Polyneuropathy ◽  
Inflammatory Demyelinating Polyneuropathy ◽  
Immune Attack
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