The Diversity of Cadherins and Implications for a Synaptic Adhesive Code in the CNS

tion, electron-dense “pegs” in the synaptic cleft can be The establishment and maintainance of synaptic asobserved emanating from thickenings of the preand sociations [is] conceived to be regulated by highly postsynaptic membranes. These universal features of specific cytochemical affinities that arise systematithe CNS synaptic junctional complex are indicative of a cally among the different types of neurons involved strongly adhesive structure, and this conclusion is convia self-differentiation, induction through terminal confirmed by cell fractionation experiments. Once formed, tacts, and embryonic gradient effects. (Sperry, 1963) the preand postsynaptic membranes resist physical