ISSN:
0003-276X
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
The effects of acute stretch, laterally applied pressure, and exterfusal contraction upon the morphology of spindles in cat muscles have been studied by making measurements from serial histological sections. Cross-sectional areas of bag and chain intrafusal fibers were taken and the circumferences of spindle capsules measured at the equatoriallevel. From these area values the relative effects on length of the measured structures were inferred. 1. Stretch was found to lengthen the capsules and both bag and chain fibers. 2. Contracture induced by use of the drug ryanodine was accompanied by shortening of both bag and chain fibers. 3. Stretch was still effective in the presence of full contracture. 4. Pressure applied to the lateral surface of the muscle affectedboth bag and chain fibers.These findings taken with other considerations demonstrate the anatomical basis for the mechanism that is commonly assumed to cause the acceleration in discharge from primary and secondary endings with stretch and the “pause” with contraction of the gross muscle. The relation to a possible pressure sensing mechanism for secondary endings is discussed.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/ar.1091560109
