Junctions In Cultures Research Articles

Choline acetyltransferase activity is increased in combined cultures of spinal cord and muscle cells from mice.

The activity of choline acetyltransferase was more than tenfold greater in combined cultures of spinal cord and muscle cells than in cultures of spinal cord cells alone. This increase was associated with the formation of functional neuromuscular junctions in culture. Counts of silver-stained cells and determinations of other enzyme activities indicated that the increased choline acetyltransferase activity was not due to nonspecific neuronal survival but reflected greater activity in the surviving neurons. Hence, muscle had a marked, highly specific trophic effect on the cholinergic neurons that innervated it.

The development of neuromuscular junctions in cultures of chick embryo tissues.

AbstractNeuromuscular junctions formed in vitro have been obtained previously only in cultures of cross‐sections of embryos. These have represented simply the further development in vitro of the anlage of neuromuscular junctions previously formed in vivo. The present experiments were designed to determine whether such junctions could form de novo in tissue culture and in organ culture from spatially separated spinal cord and skeletal muscle. Cultures of dissociated spinal cord and muscle cells could not be maintained sufficiently long to lead to differentiated neuromuscular junctions. However, when fragments of spinal cord and muscle from chick embryos of varying developmental stages were cultivated for several weeks neuromuscular junctions could be identified by phase contrast microscopy, silver impregnation, and AChE staining. The neuromuscular junctions were similar histologically and histochemically to those developing in vivo.