Ultrastructure of extrafusal and intrafusal terminals of a (dynamic) skeletofusimotor axon in cat tenuissimus muscle.
Terminals of a histologically identified beta skeletofusimotor axon in cat tenuissimus muscle were examined in semi-thin (1 micrometer thick) and ultrathin transverse sections. The beta axon supplied one extrafusal endplate and two motor endings on the nuclear bag1 intrafusal muscle fiber. The staining properties of the co-innervated bag1 and extrafusal fibers were dissimilar. The beta intrafusal and extrafusal terminals were also dissimilar by both light and electron microscopy , differing in length, mitochondrial content of the sole-plate, and folding of the post-synaptic membrane.
D000818:Animals; D002415:Cats; D008854:Microscopy, Electron; D009046:Motor Neurons / Q000648:ultrastructure*; D009047:Motor Neurons, Gamma / Q000502:physiology / Q000648:ultrastructure*