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Electron microscopic studies of serially sectioned cat spinal α‐motoneurons. IV. Motoneurons innervating slow‐twitch (type s) units of the soleus muscle
Author(s) -
Conradi S.,
Kellerth JO.,
Berthold CH.,
Hammarberg C.
Publication year - 1979
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.901840409
Subject(s) - biology , anatomy , axon hillock , axon , soleus muscle , soma , dorsum , cell bodies , neuroscience , central nervous system , skeletal muscle
Two intracellularly stained cat α‐motoneurons of the soleus‐S type (Burke et al., '74) were studied ultrastructurally. The architecture and synaptology of the cell body and proximal parts of the dendrites were analyzed from a long series of sonsecutive sections (Conradi et al., '79). Only few of the dendrites had a base diameter exceeding 10 μm. The proportion of the membrane surface of the cell body and dendrites covered by boutons was 40‐45% and 50‐80%, respectively. Out of this, 15‐20% was constituted by S‐boutons and 70‐75% by F‐boutons in both regions. In contrast to the situation in the gastrocnemius FR‐neurons (Kellerth et al., '79) the large boutons of the C‐type showed no clustering around the dendritic roots and were absent on the axon hillock. In addition, the M‐boutons of dorsal root origin were more sparse on the proximal parts on the dendrites of the soleus‐S neurons.