Upload File

introduction

2
MICROSCOPY RESEARCH AND TECHNIQUE 34~397-398 (1996) Introduction In 1871, the French pathologist Louis Antoine Ran- vier described and illustrated in peripheral myelinated nerve fibers periodic annular constrictions which inter- rupted the ensheathment of the axis cylinder (Ranvier, 1871-2). Phylogenetically, the nodes have evolved in- dependently in at least three phyla: the primitive deu- terostomes, which gave rise to the chordates, and the primitive annelid stock, from which the annelids and arthropods originated. The structure and function of nodes is very similar in all three, indicating their im- portance and appropriate design (Roots, 1984). It is a structural complex of special physiological and mor- phological significance for central and peripheral my- elinated nerve fibers, which is essential for (1) salta- tory impulse conduction, (2) mechanical stability and axonal fxation of the myelin sheath (Yu and Bunge, 19751, and (3) segregation of sodium channels to the nodal axolemma in developing individuals and in adults (Rosenbluth, 1976). The paranodal “axoglial” junction, forming a long periaxonal channel of high impedance, provides electrochemical isolation of the nodal from the internodal periaxonal milieu; this is important for the generation of action potentials at the node of Ranvier. Since the detailed monograph on the node of Ran- vier, edited by Zagoren and Fedoroff in 1984 and com- prising 392 pages, knowledge on the node appears to have been increasing exponentially. The following se- ries of articles focuses on recent progress of research into the normal and pathological development and structure of the node and paranode in man and exper- imental animals. The growing myelin lamellae adapt themselves to the expanding paranodal segment of the immature axon as shown in experimental animals (see article by Berthold) and in developing human sural nerves (see article by Schroder). At the paranode of a large myelinated fiber, only 10-25% of the myelin lamellae contact the paranodal axon membrane; the remainder are separated from the axon forming the “spines” of the “double bracelet epineux” of Nageotte (1911). This aspect should not be mistaken for patho- logic “axoglial dysjunction,” which in fact may indicate incipient segmental demyelination (see article by Gi- annini and Dyck). In recent times, immunocytochemi- cal techniques have been developed to precisely localise for the first time at the light and electron microscopic level voltage-dependent sodium channels in the nodal axolemma where they are linked to ankyrin and asso- ciated with the internal cytomatrix via spectrin (see article by England et al.). There are neural adhesion molecules (e.g., N-CAM and tenascin/cytotactin) in the nodal basal lamina, and hyaluronic acid, versicanhy- aluronectin and gangliosides GM1 and GDlb in the nodal gap; and myelin-associated glycoprotein (MAG), oligodendrocyte-myelin glycoprotein, connexin32, E- cadherin, actin, spectrin, and catenins, the ganglioside GQlb, the potassium channel, and alkaline phos- phatase in the paranodal region of the Schwann cell (see article by Scherer). In this context it is of special interest that MAG presumably plays a special role in immune mediated and connexin32 in X-linked heredi- tary neuropathy in man (whereas myelin basic protein, MBP, peripheral myelin protein kD 22, PMP22, and protein Po, are located in the compact part of the my- elin sheath, i.e., in some distance from the nodes, and are supposed or known to be associated with other types of immune mediated or hereditary neuropathies, i.e., Guillain-Barre or Miller Fisher syndrome, Charcot Marie Tooth disease type Ia, Dejerine Sottas disease, and hereditary neuropathy with liability to pressure palsies). In addition, there is an intense nodal accumu- lation of vesicular membrane compartments cytochem- ically identified as synaptophysin or synapsin I in ax- ons; actin in paranodal Schwann cell compartments appears to be related to the paranodal constrictions of axons (see article by Zimmermann). Intercellular ac- tions at the node during development and regeneration may be modified by alterations of polysialic acids (see article by Carratu et al.). Acid phosphatase activity is seen especially a t the so-called axon-Schwann cell net- work where local lysosomal degradation of transported material may take place (see article by Gatzinsky). An especially vulnerable site is the CNS-PNS transition zone (see article by Fraher). The nodes are particularly prone to stretch injuries (see article by Maxwell), an- tibody attack (see article by Thomas), and parapro- teinemia (see article by Jacobs); the abnormal proteins can lead to precipitates and a special type of separation of myelin lamellae at the intermediate line. Other pathological changes at the node of Ranvier comprise pseudonodes, swelling of myelin loops, formation of membranous bodies, abnormal arrangements of Schwann cell processes, and various cytoplasmic inclu- sions (see article by Schroder). The molecular basis of the normal nodal and para- nodal structure and of their pathological changes is being elaborated in recent years with increasing effec- tivity; it is hoped that it will be the basis for under- standing and possibly treating diseases of central and peripheral nerve fibers. “Structure of the Nodes and Paranodes in Peripheral Nerves” is aimed at offering a present day’s update of our knowledge on the nature and the pathological structure of the node and para- node. REFERENCES Nageotte, J. (1911) Betrachtung uber den tatsachlichen Bau und die kunstlich hervorgerufenen Deformationen der markhaltigen Nervenfasern. Arch. Mikrosk. Anat., 77:245-279. Ranvier, L. (1871-2) L‘histologie et la physiologie des nerfs. Arch. Physiol. Norm. Pathol., 4:427-446.

Upload: j-michael

Post on 06-Jun-2016

215 views

Category:

Documents


2 download

Report

TRANSCRIPT

Page 1: Introduction

MICROSCOPY RESEARCH AND TECHNIQUE 34~397-398 (1996)

Introduction

In 1871, the French pathologist Louis Antoine Ran- vier described and illustrated in peripheral myelinated nerve fibers periodic annular constrictions which inter- rupted the ensheathment of the axis cylinder (Ranvier, 1871-2). Phylogenetically, the nodes have evolved in- dependently in a t least three phyla: the primitive deu- terostomes, which gave rise to the chordates, and the primitive annelid stock, from which the annelids and arthropods originated. The structure and function of nodes is very similar in all three, indicating their im- portance and appropriate design (Roots, 1984). It is a structural complex of special physiological and mor- phological significance for central and peripheral my- elinated nerve fibers, which is essential for (1) salta- tory impulse conduction, (2) mechanical stability and axonal fxation of the myelin sheath (Yu and Bunge, 19751, and (3) segregation of sodium channels to the nodal axolemma in developing individuals and in adults (Rosenbluth, 1976). The paranodal “axoglial” junction, forming a long periaxonal channel of high impedance, provides electrochemical isolation of the nodal from the internodal periaxonal milieu; this is important for the generation of action potentials at the node of Ranvier.

Since the detailed monograph on the node of Ran- vier, edited by Zagoren and Fedoroff in 1984 and com- prising 392 pages, knowledge on the node appears to have been increasing exponentially. The following se- ries of articles focuses on recent progress of research into the normal and pathological development and structure of the node and paranode in man and exper- imental animals. The growing myelin lamellae adapt themselves to the expanding paranodal segment of the immature axon as shown in experimental animals (see article by Berthold) and in developing human sural nerves (see article by Schroder). At the paranode of a large myelinated fiber, only 10-25% of the myelin lamellae contact the paranodal axon membrane; the remainder are separated from the axon forming the “spines” of the “double bracelet epineux” of Nageotte (1911). This aspect should not be mistaken for patho- logic “axoglial dysjunction,” which in fact may indicate incipient segmental demyelination (see article by Gi- annini and Dyck). In recent times, immunocytochemi- cal techniques have been developed to precisely localise for the first time at the light and electron microscopic level voltage-dependent sodium channels in the nodal axolemma where they are linked to ankyrin and asso- ciated with the internal cytomatrix via spectrin (see article by England et al.). There are neural adhesion molecules (e.g., N-CAM and tenascin/cytotactin) in the nodal basal lamina, and hyaluronic acid, versicanhy- aluronectin and gangliosides GM1 and GDlb in the nodal gap; and myelin-associated glycoprotein (MAG), oligodendrocyte-myelin glycoprotein, connexin32, E- cadherin, actin, spectrin, and catenins, the ganglioside

GQlb, the potassium channel, and alkaline phos- phatase in the paranodal region of the Schwann cell (see article by Scherer). In this context it is of special interest that MAG presumably plays a special role in immune mediated and connexin32 in X-linked heredi- tary neuropathy in man (whereas myelin basic protein, MBP, peripheral myelin protein kD 22, PMP22, and protein Po, are located in the compact part of the my- elin sheath, i.e., in some distance from the nodes, and are supposed or known to be associated with other types of immune mediated or hereditary neuropathies, i.e., Guillain-Barre or Miller Fisher syndrome, Charcot Marie Tooth disease type Ia, Dejerine Sottas disease, and hereditary neuropathy with liability to pressure palsies). In addition, there is an intense nodal accumu- lation of vesicular membrane compartments cytochem- ically identified as synaptophysin or synapsin I in ax- ons; actin in paranodal Schwann cell compartments appears to be related to the paranodal constrictions of axons (see article by Zimmermann). Intercellular ac- tions at the node during development and regeneration may be modified by alterations of polysialic acids (see article by Carratu et al.). Acid phosphatase activity is seen especially a t the so-called axon-Schwann cell net- work where local lysosomal degradation of transported material may take place (see article by Gatzinsky). An especially vulnerable site is the CNS-PNS transition zone (see article by Fraher). The nodes are particularly prone to stretch injuries (see article by Maxwell), an- tibody attack (see article by Thomas), and parapro- teinemia (see article by Jacobs); the abnormal proteins can lead to precipitates and a special type of separation of myelin lamellae at the intermediate line. Other pathological changes at the node of Ranvier comprise pseudonodes, swelling of myelin loops, formation of membranous bodies, abnormal arrangements of Schwann cell processes, and various cytoplasmic inclu- sions (see article by Schroder).

The molecular basis of the normal nodal and para- nodal structure and of their pathological changes is being elaborated in recent years with increasing effec- tivity; it is hoped that it will be the basis for under- standing and possibly treating diseases of central and peripheral nerve fibers. “Structure of the Nodes and Paranodes in Peripheral Nerves” is aimed at offering a present day’s update of our knowledge on the nature and the pathological structure of the node and para- node.

REFERENCES Nageotte, J. (1911) Betrachtung uber den tatsachlichen Bau und die

kunstlich hervorgerufenen Deformationen der markhaltigen Nervenfasern. Arch. Mikrosk. Anat., 77:245-279.

Ranvier, L. (1871-2) L‘histologie et la physiologie des nerfs. Arch. Physiol. Norm. Pathol., 4:427-446.

Page 2: Introduction

398 J.M. SCHRODER

Roots, B.I. (1984) Evolutional aspects of the structure and function of the nodes of Ranvier. In: The Node of Ranvier. J.C. Zagoren, and S. Fedoroff, eds. Academic Press: Orlando.

Rosenbluth, J. (1976) Intramembranous particle distribution at the node of Ranvier and adjacent axolemma in myelinated axons of the frog brain. J. Neurocytol., 5:731-745.

Yu, R.C.-P., and Bunge, R.P. (1975) Damage and repair of the periph- era1 myelin sheath and node of Ranvier after treatment with trypsin. J. Cell Biol., 641-14.

Zagoren, J.C., and Fedoroff, S., eds. (1984) The Node of Ranvier. Ac- ademic Press: New York, 392 pp.

J. MICHAEL SCHRODER Institut fur Neuropathologie

50274 Aachen, Germany


§1.1.1 INTRODUCTION: 1. INTRODUCTION

Introducción / Introduction / Introduction

1. INTRODUCTION INTRODUCTION - Deusto

Topics Introduction 1 / 3 Introduction 2 / 3 Introduction 3 / 3

Introduction to Elasticsearch and Logstash. - KIT · PDF fileOutline 1 Introduction 2 Logstash Introduction 3 Elasticsearch Introduction 4 Conclusions Introduction Logstash ElasticsearchConclusions

 · Contents INTRODUCTION Introduction

1. INTRODUCTION 1.1 Introduction

Introduction Section I: Introduction

Introduction 1. Introduction

Introduction Chapitre 1 · Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Systems Analysis I introduction I introduction. 2Systems Analysis - Introduction Contents Introduction Introduction 3 classic phases 3 classic phases

1 Introduction INTRODUCTION - MICROCSB

Introduction to Logic Introduction

An Introduction to NSAn Introduction to NS2An Introduction

introduzione | introduction | einleitung | introduction · introduzione | introduction | einleitung | introduction | introducción | введе́ние | wstęp en Description Operation

Introduction | Introduction | Millennium Serials · 2018. 4. 17. · MARC Display | Print | Introduction | Millennium Serials INTRODUCTION Introduction This tutorial introduces the

An Introduction to NSAn Introduction to NS2An Introduction ...teerawat/publications/NS2/02-NS2.pdf · An Introduction to NSAn Introduction to NS2An Introduction to NS2 Textbook: T

1. Introduction 1. Introduction 1. Introduction 1 ... · Introduction 1. Introduction 1. Introduction 1. Introduction 6061B0242401. The Phone Screen From the Phone screen, you can

Introduction: Definition Introduction: Philosophy

An Introduction for An Introduction for Introduction for ......An Introduction for An Introduction for Introduction for TeachersTeachersTeachers . exChange, Blackburn Cathedral’s

VisionaryScancombinesarichsetofqualitycontrolandproductivi ... · Introduction Introduction VisionaryScancombinesarichsetofqualitycontrolandproductivityfeatureswithasimpleinterfacedesignedspecificallyforscanningandcodingdepositionexhib-

General introduction 1.1 Introduction

Module: Introduction...Module: Introduction Page: Introduction CC0.1 Introduction Please give a general description and introduction to your organization. Providing electrical, hydraulic

CrowPiwithMineCraftPiEdition · 2 CrowPiwithMineCraftPiEdition-Introduction-MinecraftPiEdition-Introduction-Whatyouwillneed-Introduction-RunningMinecraft-Introduction

Introduction and Thesis Introduction - …...1 Introduction and Thesis Introduction: The introduction relates the topic to the main point of the essay. The introduction is composed

Industry introduction Industry introduction Company introduction Company introduction Production introduction Display time time content

PRODUCT INTRODUCTION Company Introduction

1. INTRODUCTION • INTRODUCTION • EINFÜHRUNG • INLEIDING • INTRODUCCIÓN … · 2016-12-16 · 1. INTRODUCTION • INTRODUCTION • EINFÜHRUNG • INLEIDING • INTRODUCCIÓN

Introduction Introduction (ctnd.)

INTRODUCTIONS (LEADS) Creative introduction Action introduction Dialogue introduction Personal introduction Question introduction Quotation introduction

Introduction and Welcome€¦ · Introduction and Welcome Introduction 4

Introduction Introduction Introduction Introduction

INTRODUCTIONS (LEADS) Academic introduction Creative introduction Action introduction Dialogue introduction Overarching societal statements Personal introduction

Introduction - University of Cambridge · Introduction. Introduction

Introduction Introduction to Brittle Deformation