Survival of newly postmitotic motoneurons is transiently independent of exogenous trophic support.

摘要: We compared the survival requirements of early- and late-born motoneurons from E5 chicken spinal cord. Density gradient centrifugation followed by immunopanning using SC1 antibody allowed us to purify two size classes motoneuron. Large retained 6.8% metrizamide were shown BrdU labeling in ovo be born on average 1.5 d earlier than small recovered pellet. both biochemically functionally more mature: they expressed higher levels choline acetyltransferase low-affinity neurotrophin receptor, had an acute requirement for trophic support muscle-derived factors. After 24 hr culture basal medium, all early-born died, whereas 60% survived. Small can develop into large ovo, suggesting that represent a general transitional stage motoneuron development. Our results suggest defined period elapses between birth its acquisition dependence, possibly corresponding time required target innervation. This property may have important consequences timing regulation developmental death.