Quantitative changes in nuclear pores and chromatoid bodies induced by neuropeptides during cell differentiation in the planarian Dugesia japonica.

Neuropeptides were used in experiments to assess their effects on planarian cells. Intact and decapitated planarians exposed to 10(-6) M neuropeptides for two days were examined electron microscopically and quantitative changes in the nuclear pores and chromatoid bodies in various types of cells were ascertained. The data clearly indicated the diversity of effects produced in planarian cells by neuropeptide treatments. The number of nuclear pores increased considerably in each cell type treated with neuropeptides. In particular, the effects of neuropeptides were strongest in differentiating cells which were forming the regeneration blastema. Neuropeptide-treated cells also experienced a dramatic increase in the number of chromatoid bodies. The results obtained in this study suggest that synthesis of RNAs leading to increases in the numbers of nuclear pores and chromatoid bodies is facilitated in neuropeptide-treated cells which are undergoing cell differentiation. The different mechanisms of the effects induced in undifferentiated cells by neuropeptides are discussed.