THE RELATIONSHIP BETWEEN THE PROLIFERATING ABILITY AND ACETYLCHOLINESTERASE ACTIVITY OF THE NEURAL TUBE CELLS IN EARLY CHICK EMBRYOS

Abstract

Using a new method of performing ³H-thymidine autoradiography and histochemical demonstration of acetylcholinesterase (AChE) activity on the same sections, the relationship between the proliferating ability and AChE activity of the neural tube cells was studied in early chick embryos.
In 1.5-day embryos (stage 10), almost all the cells constituting the neural tube showed weak AChE activity, namely, the reaction products were detected along the nuclear membrane. Since these cells were labeled with ³H-thymidine they had proliferating ability. In 2-day embryos (stage 13), a few cells showing an intense reaction were first found near the basement membrane at the cervical level, in which the reaction products were demonstrated not only along the nuclear membrane but also in the cytoplasm. They were round in shape and not labeled with ³H-thymidine. They were regarded as neuroblasts. In addition to these cells, a few spindle-shaped cells having the reaction products along the nuclear membrane and in the cytoplasm were demonstrated in the ependymal layer (matrix). Up to four hr after the injection of ³H-thymidine, these cells were not labeled and after eight hr some of them were first labeled. This indicated that they were newly formed neuroblasts, having lost their proliferating ability.