Postnatal development of cell columns and their associated dendritic bundles in the lumbosacral spinal cord of the rat. II. The ventromedial cell column.
Postnatal formation of the ventromedial dendrite bundle (MDB) in the rat lumboscral cord was examined quantitatively with Golgi-Cox impregnation. At birth, dendrites of motoneurons in the MDB had not achieved their total length, and had not begun to form bundles. Dendrites projected from the soma in a radially symmetric fashion. At 5 days, dendritic shafts reoriented into the longitudinal plane, and by 10 days of age dendrite bundling was apparent. Between day 1 and 60, primary, secondary and tertiary dendrites from motoneurons in the MDB increased both in number and in length, and the MDB became more compact and intertwined. Dendritic growth and bundling was complete by two months of age. The dendritic spatial arrangement of the MDB, as well as the LDB, may provide an important anatomical substrate for receiving appropriate developing axonal inputs. In turn, it is likely that specific incoming axonal inputs that arrive in this cell column early in development may signal the redirection of dendrites of ventromedial motoneurons into the longitudinal plane.
D000818:Animals; D003712:Dendrites; D005260:Female; D008297:Male; D009046:Motor Neurons / Q000166:cytology*; D051381:Rats; D013116:Spinal Cord / Q000254:growth & development*; D013997:Time Factors