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. 2006 Feb 15;26(7):1896–1905. doi: 10.1523/JNEUROSCI.3202-05.2006

Figure 3.

Figure 3.

Phospho-SMAD immunolabeling demonstrates loss of BMP signaling in the cerebellum of Bmpr1a;Bmpr1b knock-out mice. A, Immunoreactive cells are detected in the rostral rhombic lip at 10.5 dpc in normal mice (arrow). B, In mutant embryos, phospho-SMAD immunostaining is lost in the rostral rhombic lip (arrow). C, At 13.5 dpc in normal embryos, immunoreactive cells are detected in the ventral cerebellar anlage within and above the neuroepithelium (arrow). In addition, immunoreactive cells are located dorsally in leptomeninges (asterisk). D, In the mutant mouse, phospho-Smad immunostaining demonstrates that BMP signaling has been abrogated in the vast majority of cells within the cerebellar anlage (arrow). However, a few positive cells are located along the dorsal side (arrowhead) of the neural tube in a region where the granule cells are migrating to form the EGL. Immunolabeling in the leptomeninges is unaffected (asterisk). E, Postnatally, phospho-SMAD-immunolabeled cells are detected in migrating granule cells and in the IGL of normal mice, which lies deep to the PCL (arrows). F, In the P0 mutant, phospho-Smad immunolabeling is drastically reduced. However, a few labeled cells are detected within or proximal to the rhombic lip (arrow) and a few cells deep in the cerebellum (arrowheads). G, Double immunolabeling with phospho-SMAD (green) and Zic1/2 (red) in the cerebellum of a normal mouse at P0. Double immunostained cells are located predominantly in the IGL and in migrating granule cells (arrows). However, a few cells are detected in the EGL (the dense cell layer located at the top of the panel). H, Area depicted in G showing immunostaining for Zic1/2 alone to demonstrate that two classes of Zic1/2-immunopositive cells can be detected that label intensely (arrowhead) or lightly (arrows). I, Double immunolabeling with phospho-SMAD (green) and calbindin (red) in a section of the cerebellum of normal mice at P0 counterstained with DAPI (blue). Virtually no double immunostained cells are detected in the cerebella, whereas single calbindin-labeled positive Purkinje cells are found in the cerebella. These results demonstrate that phospho-SMAD is detected in granule cells that have migrated away from the proliferative zone of the EGL and are in the process of differentiating into mature granule cells. Scale bars: A, 250 μm; C, E, I, 100 μm; G, 50 μm. pSMAD, Phospho-SMAD.