Fig. 2

Specific patterns of DCC and UNC-5 expression in the X. laevis central nervous system. Immunostaining with antibodies to UNC-5 (red) and DCC (green) revealed specific patterns of expression of the netrin-1 receptors in stage 45 tadpoles. a–g UNC-5 (red) and DCC (green) immunoreactivity in the forebrain (a), pre-tectum (b), caudal tectum (e), hindbrain (f), and rostral spinal cord (g) demonstrate a specific pattern of expression for each of these receptors within subpopulations of neurons in the central nervous system. c UNC-5 immunostaining (red) localizes to subpopulations of neurons in the dorsal tectum, lateral-ventral midbrain, ventral midline (vm), and infundibulum (if). d DCC immunoreactivity (green) is localized in dorsal tectal neuron cell bodies and processes in the tectum and ventral midline, as well as in the tectal neuropil (np). e, f Note the specificity of immunostaining and co-localization of UNC-5 and DCC expression in subpopulations of cells in the caudal tectum (e) and hindbrain (f) and the localization of DCC receptors to discrete fiber tracts (arrows). g, h UNC-5 (red) and DCC (green) immunoreactivity in the rostral (g) and caudal (h) spinal cord is localized to fiber tracts and ventral midline in agreement with published observations in Xenopus and other species (for review, see [42, 5, 43–45]). DCC immunoreactivity in the spinal cord is similar when staining with antibodies directed against the extracellular (g) or intracellular (h, bottom) domains of DCC. Counterstaining with DAPI (blue) serves to distinguish nuclear staining from UNC-5 (red) and DCC (green) expression in cell bodies and fiber tracts. Scale bars: 50 μm