Compensatory responses in the development of the brachial lateral motor column in triploid Rana pipiens.

Responses of the lateral motor column (LMC) in the frog spinal cord to various experimental manipulations generally are manifested in an adjustment of the number and sizes of the motor neurons. Analysis of the brachial LMC in induced-triploid Rana pipiens larvae as compared to diploid controls revealed a significant increase in nuclear size with a concomitant reduction in cell counts at all stages of development examined. These compensatory responses of the LMC to polyploidy in normal size frog larvae are consistent with results reported for other amphibian polyploid tissues and serve as a basis for exploring mechanisms of plasticity in the developing central nervous system.