[Glycogen depletion produced in intrafusal nuclear bag muscle fibers by brief large-amplitude muscle stretches].

The glycogen content of the three types of intrafusal muscle fibre was studied with histochemical techniques in cat muscle spindles of superficial lumbrical muscles after a very large number of brief large stretches. Zones of glycogen depletion were observed in a high proportion of nuclear bag fibres, notably in bag 1 fibres, but not in chain fibres. These observations suggest that stretching of bag fibres by itself may activate these fibres.