Anatomical and physiological development of the Xenopus embryonic motor system in the absence of neural activity

Abstract

Embryos of Xenopus laevis were continually immobilized by immersion in solutions of either chloretone or lidocaine, from the late neural-fold stage to the approximate time of hatching. Such treatment has been shown to result in only transient quantitative effects on swimming behavior. Chronic immobilization was without either immediate or long-term effect on the ventral root output exhibited during "fictive" swimming episodes. Development under these conditions of diminished or absent neural activity similarly had no effects on a number of measures of the size and complexity of motoneuron dendritic arborizations. These results support the premise that the early development of specific neuronal morphology and connectivity may be largely independent of functional activity.