Fig. 8. EYFP-labelled neurons show ventricle-directed migration in close apposition to nestin-positive radial fibres. (A,B) EYFP-labelled cells (left panels) in the myelencephalon (A) and the metencephalon (B). Subsets of migrating EYFP-labelled PC neurons associated with nestin-positive fibres (purple). Some nestin-positive fibres also extended horizontally (arrowheads in B). (C,D) Left panels in C and D show higher-magnification views of the rectangular areas in A and B, respectively. Middle panels show nestin immunostaining. Arrowheads indicate radially extending leading processes of EYFP-labelled neurons apposed to nestin-positive fibres (middle panels) in the myelencephalon (C) and metencephalon (D). An arrow in the middle panel of D shows a tangentially extending fibre. An EYFP-labelled neuron in the pontine region (green) extended branched leading processes that were oriented tangentially and radially, with both branches closely apposed to nestin-positive fibres (arrowheads in right panel of D). EYFP was electroporated into the left lRL. (E,F) Electron micrographs, taken in the pontine region, of a presumptive PC neuron making contact with a radial fibre (arrowheads in E). F represents higher-magnification view of the rectangle in E. Asterisks in E and F indicate the nucleus of the neuron. The neuron contacts the radial fibre along a length of its plasma membrane. Transverse sections of E15.5 embryos. Right panels in A-D show a merged view with nestin immunostaining of the same section. The ventricle is upwards; the pia is downwards. LRN, lateral reticular nucleus; RF, radial fibre. Scale bars: in B, 50 µm for A,B; in D, 35.2 µm for C and 20 µm for D; in E, 2 µm; in F, 250 nm.