Note the axon foot "AX" with mitochondria and smaller synaptic vesicles, which discharge acetyl choline into the narrow synaptic cleft "SC". The acetyl choline receptors are concentrated in the thickened muscle sarcolemma immediately beneath the axon foot. Acetyl choline esterase is located deeper in the synaptic clefts. Contractile filaments are visible in the muscle cell, lower right.
Note the abnormal axon morphology "AX" and the greatly enlarged synaptic clefts "SC", filled with densely staining material. Contractile filaments are visible in the muscle cell, lower right.