During neuromuscular synaptogenesis nicotinic acetylcholine receptors (nAChR) diffusely arranged in the postsynaptic membrane preferentially sequester into aggregates. With time these aggregates come to collocalize with the post-junctional folds where they function as neurotransmitter receptors. I am interested in the molecular mechanism which maintains this integral membrane protein in place.I present a high resolution account of the muscle membrane/cytoskeleton at the, nAChR plaques.Cocultures of myocytes and neural tube neurons from stage 22 Xenopus laevis embryos develop a reasonable number of ventral surface junctions. nAChRs also aggregate in muscle cultures without neurons. Receptor plaques are identified by labeling with fluorescent alpha-bungarotoxin (BTX)(Fig. 1a, 2a). In order to gain access to the cytoplasmic surface the cultures are incubated in a ZnCl2 solution, which stabilizes the R-rich ventral membrane areas, then sheared with a stream of ice-cold buffer. After immediate fixation the cellular fragments are ready for ultrastructural processingor immunocytochemistry.The quick-freeze, deep-etch, rotary-shadow technique is best suited for high-resolution en-face observation of these preparations. Improvements in the original technique were necessary to produce a satisfactory and informative replica.