The spinal cord, dorsal root ganglia and sympathetic ganglia from the brachial region of a chick cryosection at stage 23 (Hamburger and Hamilton numbering) were identified with the mouse monoclonal anti–human neuronal protein HuC/HuD antibody (Cat. no. A21271) and visualized with fluorescein-labeled goat anti–mouse IgG antibody (Cat. no. F2761). The primary antibody recognizes an antigen localized to neuronal cell bodies and is ideal for identifying and counting neurons in both early and late development. Human, mouse, avian and zebrafish tissues have all demonstrated similar neuron-specific labeling patterns. Image contributed by Michael Marusich, Monoclonal Antibody Facility, University of Oregon, Eugene, Oregon.