Scanning electron microscopic observation on the equatorial region of the rat intrafusal muscle fibres, especially on the subsarcolemmal sarcoplasmicreticulum
A. Sohn et al., Scanning electron microscopic observation on the equatorial region of the rat intrafusal muscle fibres, especially on the subsarcolemmal sarcoplasmicreticulum, J ELEC MICR, 48(5), 1999, pp. 659-663
We examined intracellular structures in the equatorial region of the muscle
spindles of rat soleus muscles by scanning electron microscopy, paying par
ticular attention to the ultrastructure of the sarcoplasmic reticulum (SR)
beneath the sarcolemma. The subsarcolemmal SR was more developed in nuclear
chain fibres than in nuclear bag fibres as was reported in the sleeve and
extracapsular regions. In addition, the subsarcolemmal SR of the chain fibr
e formed a fenestrated sheet, whereas that of the bag fibre organized a lay
er of fenestrated bands beneath the sarcolemma where the sensory nerve endi
ngs are associated. No T-tubules were discerned in the subsarcolemmal SR of
both fibres, which may be concerned with the little contraction of the equ
atorial region.