In vitro synaptic maturation.

Cocultures of spinal cord neurons and muscle cells taken from rat embryos were used for in vitro reproduction of embryonic synapses. This system did not display the synaptic maturation characteristics of postnatal development: decreased multiple innervation and the presence of a developed subneural apparatus. Studies on cultures consisting of 3 cell types (muscle cells, nerve cells, Schwann cells), or on co-cultures (muscle cells, nerve cells), in the presence or absence of a monoclonal antibody directed against an antigen from Schwann cells, have shown that Schwann cells participate in synaptic maturation and in the elimination of superfluous synapses. The synapses were visualised for optical microscopy by co-localisation of acetylcholinesterase (AChE) spots and acetylcholine receptor (AChR) clusters.