Aggrecan immunoreactivity in various brain stem regions at various postnatal ages. A: densitometry. Brain regions include nucleus tractus solitarius (nTS), hypoglossal motor nucleus (XII), dorsal motor nucleus of the vagus (DMNV), cuneate nucleus (CN), and area postrema (AP). CC, central canal. Values are means ± SE; n = 6 at P5, 9 at P10, 8 at P15, 7 at P20 , and 5 at P90. *Statistically different from preceding (younger) age group (P < 0.05, by One-way ANOVA). B: representative images of brain stem regions at P5, P10, P15, P20, and P90 (adult). Scale bar = 100 μm.