The formation of synaptic connection is a central issue in the development of the nervous system. The formation of the neuromuscular junction offers a simple system for understanding synaptic development. This can be conveniently studied in tissue culture. In Professor Peng's laboratory, muscle cells and neurons from amphibian embryos are placed into tissue culture. When neurites contact the muscle cell, development of the neuromuscular junction follows. This is manifested by the formation of acetylcholine receptor clusters in the postsynaptic membrane and the development of synaptic vesicle clusters in the presynaptic terminal. The development of these synaptic specializations in culture is followed with a variety of techniques including light and electron microscopy, electrophysiology, immunocytochemistry, and molecular biology. Professor Peng is particularly interested in the signal that is communicated between nerve and muscle which leads to synaptic differentiation and the cellular and molecular mechanisms used by these two cell types in the assembly of the specializations for neuromuscular transmission.