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PRACTICAL ROADMAP MUSCLE
WJ van der Spuy
MUSCLE
• Skeletal (striated) • Cardiac (striated) • Smooth
• Identification based on
– Fiber size, shape and presence/absence of branching – Number, shape and position of nuclei – Presence or absence of cross-striations
MUSCLE Skeletal Cardiac Smooth
Cell Elongated Branching Spindle-shaped
Nucleus Multiple peripheral Single or bi-nucleated central
Single central
Striations Cross-striated Cross-striated & Intercalated disks
None
Motor Control Voluntary Involuntary Involuntary
SKELETAL MUSCLE
• Slide 76 Striated Skeletal Muscle – Tongue – Iron haematoxylin stain
Organisation
Epimysium - surrounding muscle
Perimysium - surrounding fascicle
Endomysium - surrounding muscle fibre
Scanning Electron Micrograph – WJ van der Spuy – MSc
100µm
Muscle fibre
Fascicle
Fibre Orientation
Longitudinal section
Transverse section
Identification
Muscle fibre
Muscle fibre
Multiple peripheral nuclei
Cross-striations Fibroblast nuclei in connective tissue
sheath
Striations
A band (dark striation) bisected by light H band
I band (light striation) bisected by dark Z line
SKELETAL MUSCLE
• Slide 50 Musculo-tendinous junction – H&E stain
Musculo-tendinous Junction
Dense regular connective tissue Skeletal Muscle
Musculo-tendinous junction with fibres inserting obliquely into tendon
SKELETAL MUSCLE
• Slide 4 Neuromuscular (myoneural) junction – Snake – H&E and gold impregnation staining
Neuromuscular Junction
Axon Boutons (neuromuscular junction)
Motor Nerve (neuromuscular bundle in longitudinal section) Striated skeletal
muscle fibres
Neuromuscular bundle (transverse section)
Micrograph – WJ van der Spuy – MSc Stain: Toluidine blue pH=11.5
Blood vessel
Neuromuscular Junction
Axon boutons
Motor nerve
Muscular Dystrophy
• Limb-Girdle Muscular Dystrophy type 2B (LGMD2B)
• Increased rate of regeneration in response to ongoing degeneration of muscle
• Characterised by: – Variation in fiber size – Necrosis of muscle tissue – Revascularisation – Inflammatory cell infiltration – Phagocytosis of necrotic debris – Proliferation of mononuclear muscle precursors – Fusion of precursors to form myotubes
LGMD2B CN: Central nucleus Regenerating fibre
FS: Fibre splitting Early hyperplasia
FL: Fibre lobulation Late hyperplasia
LI: Leukocyte infiltration Inflammation
NF: Necrotic fibre Degenerating fibre
PI: Postnecrotic infiltrate Clearing debris after degeneration
SC: Satellite cell Mononuclear muscle precursor – regenerative ability
PN: Peripheral nucleus Mature fibre
Micrograph – WJ van der Spuy – MSc Stain: Toluidine blue pH=11.5
CN FL
PI
PN
FS
NF
SC 10µm
LI
CARDIAC MUSCLE
• Slide 57 Heart (interventricular septum) – Iron haematoxylin stain
Fibre Orientation
Longitudinal section Transverse section
Identification
Cross-striations
Fibre branching
Intercalated discs
Central nuclei
Interventricular Septum
Endocardium
Purkinje fibres
Myocardium with ordinary cardiac muscle fibres
Capillaries with black stained RBCs
Lumen of left ventricle
Purkinje Fibres
Pale-staining fibres
Large glycogen space around nuclei
Nucleus
Ordinary Cardiac Muscle Fibres
Dark-staining fibres
Smaller glycogen spaces around nuclei
Nucleus
CARDIAC MUSCLE
• Slide 86 Heart – H&E and elastic stain
Interventricular Septum
Endocardium
Purkinje fibres
Myocardium with ordinary cardiac muscle fibres
Interventricular Septum
Purkinje fibres Myocardium with ordinary
cardiac muscle fibres
Large glycogen space around nucleus
Nucleus
Small glycogen space around nucleus
Nucleus
SMOOTH MUSCLE
• Slide 10 Smooth muscle – Uterus (baboon) – H&E stain
Overview
Endometrium Myometrium with smooth muscle
Fibre Orientation
Longitudinal section
Transverse section
Identification
Cigar-shaped nucleus centrally located in spindle shaped fibre
Longitudinal section
Transverse section
Smooth Muscle vs. Connective Tissue
Blood vessel with smooth muscle wall
Irregular dense connective tissue
Myometrium with smooth muscle