Fig. 7. Expression of BMP receptor mRNAs at postnatal days 4 and 14. BMPR-IA mRNA is widely distributed in theP4 (a) and P14(b) mouse brains. Notice that the expression pattern within the thalamus changes from a homogeneous pattern atP4 (arrow) to expression within specific nuclei at P14 (arrow). The expression ofBMPR-IB is restricted to the anterior olfactory nuclei at P4 (c) and P14(d). The expression of BMPR-II is seen within the hippocampus, cerebellum (arrow), and mitral cell layer of the olfactory bulb at P4(e) and P14(f). Notice that all three receptors are specifically expressed within the ependymal layer of the SVZ atP4 (a, c, e; arrowhead), but not at older stages, such as P14 (b, d, f; arrowhead). BMPR-II is expressed within the cerebellum in the postnatal period at higher levels than BMPR-IA. g, h, Controlsections hybridized with BMPR-IA sense probe showing background labeling. Scale bars: a, c, e, g, 2 mm; b, d, f, h, 2 mm.