Atlas of the Ultrastructure of Diseased Human Muscle

W G P Mair, F M S Tomé

• Publisher: Elsevier
• Year: 2013
• Print ISBN: 9780443008313
• eBook ISBN: 9781483280998
• Topic: Biological Sciences
• Subtopic: Anatomy
• Index: Biological Sciences

Atlas of the Ultrastructure of Diseased Human Muscle provides a general view of the ultrastructure of normal and diseased human muscle. This book contains five chapters that illustrate the changes that take place in common pathological conditions and outline the patterns of change, which occur in particular diseases. Chapter 1 describes the ultrastructure of normal striated muscle and the extra-ocular and cardiac muscle. This chapter also deals with skeletal and cardiac muscle of the human fetus. Chapter 2 examines the changes in the ultrastructure of muscle fibers, including changes in myofibrils, mitochondria, lipid bodies, plasma, and basement membranes. Chapters 3 and 4 evaluate the changes in blood capillaries, interstitial tissue of muscle, nerves, motor end plates, and muscle spindles. Chapter 5 discusses the ultrastructural changes in various muscle diseases, such as denervation atrophy of muscle, muscular dystrophies, polymyositis, and congenital myopathies.

CHAPTER 1

Normal Striated Muscle

Publisher Summary

This chapter reviews the ultrastructure of muscle. Skeletal muscle fibers are multinucleated cells bounded successively by plasma and a basement membrane. Collagen fibers, blood vessels, and nerves lie between the muscle fibers. The bulk of the muscle fiber consists of myofibrils, which are the contractile elements of muscle. They lie parallel to the long axis of the fiber and run almost its whole length. The myofibrils display alternating dark anisotropic or doubly refractile A-bands and clear isotropic I-bands that are not doubly refractile. Muscle cells arise from undifferentiated mononucleated cells, that is, the myoblasts, which fuse to form multinucleated cells and differentiate into adult muscle fibers. In the same muscle of the fetus from early stages of development, cells occur simultaneously at different stages of differentiation. The chapter discusses cardiac muscle of adult and fetus. Cardiac muscle resembles skeletal muscle in that the myofibrils of both are striated. Cardiac muscle fibers are, however, shorter and smaller in diameter than skeletal muscle fibers.

The structure of skeletal muscle has interested many workers over the past century and a considerable addition to our knowledge of its structure and function followed the introduction of electron microscopy in the pursuit of the study of normal and diseased muscle. Numerous authors studied the ultrastructure of muscle, and important amongst the reports of some of the early investigators in experimental animals are those of Draper and Hodge (1949), H. E. Huxley (1953), Bennett and Porter (1953), Ruska (1954), Hodge, H. E. Huxley and Spiro (1954), Bennett (1955), A. F. Huxley (1957a) and Hodge (1960), and in normal human muscle that of van Breemen (1960a). More recent reviews of the ultrastructure of muscle have been reported by Wilkie (1968), Price (1969) and Fardeau (1969a). The works of many important contributors to our knowledge of the ultrastructure of muscle are mentioned throughout this chapter.

SKELETAL MUSCLE FIBRES

Skeletal muscle fibres are multinucleated cells bounded successively by a plasma and a basement membrane. Collagen fibres, blood vessels and nerves lie between the muscle fibres.

Muscle fibres are fusiform in shape and of varying length depending on the length of the muscle which they form; however, individual fibres in the same muscle may also vary in length. The diameters of the muscle fibres vary between 10 and 100 μ.

The bulk of the muscle fibre consists of myofibrils (Plates 1 and 2) which are the contractile elements of muscle. They lie parallel to the long axis of the fibre and run almost its whole length. In normal human muscle the diameter of the myofibrils varies between 0·5 and 1 μ. The myofibrils display alternating dark anisotropic or doubly refractile A-bands and clear isotropic I-bands which are not doubly refractile. In the middle of the A-band is a lighter zone, the H-zone (Hensen’s stripe), in the centre of which is the M-line (Mittelscheibe). Running through the centre of the I-band is the dense Z-line (Zwischenscheibe). In longitudinal sections of human muscle the Z-lines are commonly 800 Å wide. In cross section the Z-line has a lattice pattern. The ultrastructure of the Z-line has been studied by various authors including Knappeis and Carlsen (1962), Auber and Couteaux (1963), Reedy (1964), Kelly (1967) and Landon (1970). The distance between two Z-lines is called a sarcomere, which in resting human muscle measures about 2·3 μ but may vary from 2 to 3·8 μ, depending on whether the muscle is contracted or relaxed. The A-band is of fixed length about 1·5 μ, whereas the I-band varies in length according to whether the muscle is contracted or relaxed. Normally the Z-lines, and I- and A-bands of adjacent myofibrils lie in series (Plate 1). The Z-lines of adjacent myofibrils are not continuous with each other, nor do they extend to the plasma membrane except at the myotendinous junction. Myofibrils are formed of thick and thin myofilaments. The myofilaments in the I-band are thin, some 60 Å in diameter and about 1·0 μ long; they extend into the A-band, which contains also thick filaments of about 160 Å in diameter and 1·5 μ long. In the A-band the thick filaments are arranged in an hexagonal pattern, and each thick filament is also surrounded by six thin filaments. In relaxed muscle the H-zone is evident since it does not contain any of the thin filaments of the I-band. During contraction and relaxation of the muscle the thin filaments slide between the thick myofilaments (H. E. Huxley, 1953; A. F. Huxley and Niedergerke, 1954; and H. E. Huxley and Hanson, 1954). The sarcomere shortens during contraction of muscle resulting in diminution in length of the I-band and the H-zone, while in relaxation the I-band and the H-zone increase in length and consequently the whole sarcomere becomes longer. The thick filaments at the M-line are connected by short M-line bridges which are linked by thin M-line filaments which are limited to the width of the M-line (Knappeis and Carlsen, 1968; and Dos Remedios, 1970). Between each thick filament and the six thin filaments around it t...

Table of contents

• Cover image
• Title page
• Table of Contents
• Inside Front Cover
• Copyright
• Foreword
• Preface
• Chapter 1: Normal Striated Muscle
• Chapter 2: Changes in Muscle Fibres
• Chapter 3: Changes in Blood Capillaries and Interstitial Tissue of Muscle
• Chapter 4: Changes in Nerves, Motor End Plates and Muscle Spindles
• Chapter 5: Changes in Various Muscle Diseases
• References
• Index