Electron microscopic studies of serially sectioned cat spinal α‐motoneurons. III. Motoneurons innervating fast‐twitch (type fr) units of the gastrocnemius muscle

Publisher Website
Google Scholar
Abstract
Two intracellularly stained cat gastrocnemius α‐motoneurons of the FR‐type (Burke et al., '73) were studied ultrastructurally. The architecture and synaptology of the cell body and proximal parts of the dendrites were analyzed from a long series of consecutive sections, according to a method presented in a preceding paper (Conradi et al., '79a). Several of the dendrites had a base diameter exceeding 10 μm. The proportion of the surface covered by boutons was 40‐50% for the cell body and about 80% for the proximal dendrites. In both regions, about 20% of the boutons were of the S‐type and 70% of the F‐type. The large C‐boutons were clustered around the dendritic roots and were also present on the axon hillock. M‐boutons of dorsal root origin were located on the proximal parts of the majority of the dendrites.