SkeletalmuscleinlongitudinalsectionShowthe striationinthe musclecells.PSPstain11NEX
11 v Skeletal muscle in longitudinal section. v Show the striation in the muscle cells. PSPstain
Myofibrif:LMThefiber is filled withparallel myofibrils that extend the lengthofthe cell,and have alternate light and darkbandsThe cross-bandings of adjacent myofibrils are aligned with eachothersothatthebanding is seenacrossthewholefiber.Sothemusclefibershows cross-striations ofalternatinglight anddarkbands.Thedarkerbands are calledAbandsThe lighter bands are called IbandsEachIbandsisbisectedbyadarktransverseline,theZ lineThe smallest repetitive subunit of the contractileapparatus,thesacromere,extendsfromZ linetoZline12
12 Myofibril: LM ¬ The fiber is filled with parallel myofibrils that extend the length of the cell, and have alternate light and dark bands. ¬ The cross-bandings of adjacent myofibrils are aligned with each other so that the banding is seen across the whole fiber. ¬ So the muscle fiber shows cross-striations of alternating light and dark bands. The darker bands are called A bands The lighter bands are called I bands Each I bands is bisected by a dark transverse line, the Z line. * The smallest repetitive subunit of the contractileapparatus, the sacromere,extends from Z line to Z line
SkeletalmuscleLongitudinalsectionof skeletal musclefibersNotethe dark-stained Abands and the light-stained13I bands, whichare crossed byZlines
13 v Longitudinal section of skeletal muscle fibers. v Note the dark-stained A bands and the light-stained I bands, which are crossed by Z lines. Skeletal muscle
SkeletalmuscleEM: Ultrastructure of skeletal muscle fibers1.Myofibrils2.Transversetubules3.Sarcoplasmicreticulum4.Othercomponents#: myoglobin2glycogenribosomemitochodria
14 EM: Ultrastructure of skeletal muscle fibers 1. Myofibrils 2.Transverse tubules 3. Sarcoplasmic reticulum 4. Other components myoglobin glycogen ribosome mitochodria 2 1 3 Skeletal muscle
1.myofibrils:1-2um in diameterLong, parallel ,cylindrical filamentousHZAbundlesAband:M line,HbandIband:Z lineSarcomere1/2 I +A + 1/2 Ishortest contractile unitofskeletalmuscle
15 1.myofibrils: v 1-2um in diameter v Long, parallel , cylindrical filamentous bundles v A band: M line, H band, v I band: Z line * Sarcomere: v 1/2 I + A + 1/2 I v shortest contractile unit of skeletal muscle