Some morphological features of the myoneural junctions in certain normal muscles of the rat

Abstract

In frozen sections and whole mount preparations of the normal soleus, diaphragm, or intercostal muscles of the rat, myoneural junctions of different AChE and silver staining intensities were regularly observed. Muscle fibers of different diameters showed end-plates of varying staining intensities. No correlation was found between a certain staining intensity and diameter of the end-plates or between muscle fiber diameters and the ratio of pale to strongly stained end-plates. There was, however, a tendency for the smaller muscle fibers to have end-plates of smaller mean diameter than those in the larger muscle fibers.

Patterns of motor innervation in the pectoral muscle of adult Xenopus laevis: evidence for possible synaptic remodelling.

“…The similarity between the immature looking endings and the terminals formed by regenerating axons could indicate cases of synapse formation in normal mature muscles. These findings, together with the observation of morphological signs of regression in some motor endings, support the view of Barker & Ip (1965), Tuffery (1971) and Ip (1974), that adult muscles are subjected to a continuous process of synaptic degeneration and regeneration (see also Cardasis & Padykula, 1979). In agreement with this interpretation, clear electron microscopic evidence of synaptic degeneration in normal adult animals has been obtained in the central nervous system of the rat (Sotelo & Palay, 1971) and in the ciliary muscle of the monkey (Townes-Anderson & Raviola, 1978).…”

Size of Porcine Motor End-Plates Determined by Acetyl-Cholinesterase Staining

“…In general, larger muscle fibers are innervated by larger motor end-plates (14), and ample evidence exists to support the positive correlation between area of the motor end-plate and size of the muscle fiber (4,7,9,10). Some complications arise, however, since different types of motor terminals innervate different types of muscle fibers (11,13).…”