Fig. 6. Mis-expression of EGFRs in vivo at E14.5. The laminar and regional positions of cells infected in utero with control or EGFR virus were determined 3-4 days after infection. (A) Illustration of regional divisions. M, medial; DM, dorsomedial; D, dorsal; L, lateral; VL, ventrolateral. For control virus, 2757 cells in five embryos were counted; for EGFR virus, 3103 cells in 4 embryos were counted. (B) Regional distribution of infected cells in cortex (dorsal, ventrolateral) and olfactory bulb (OB). Note that mis-expression of EGFRs does not promote migration to the olfactory bulb via the RMS or the VL cortex via the LCS. (C) Laminar positions of infected cells in dorsal cortex. VZ, ventricular zone; SVZ, subventricular zone; IZ, intermediate zone; sp/wm, subplate/white matter; cp-l, lower half of cortical plate; cp-u, upper half of cortical plate; MZ, marginal zone. More of the EGFR-infected cells were located in sp/wm and MZ than control-infected cells (28.9±7.5 versus 2.2±1.9; P=0.01). By contrast, more control-infected cells were located in the inner half of the cerebral wall (VZ+SVZ+IZ) than EGFR-infected cells (87.4±5.9 versus 35.6±9.9; P=0.01). (D) Micrograph of cells infected with control virus. Several cells in the inner half of the cerebral wall are shown (arrow points to cells in VZ). (E) Micrograph of cells infected with EGFR virus. Several cells in the sp/wm are shown (arrows). (F) The laminar positions of infected cells in the olfactory bulb indicated that within the bulb, EGFR-misexpression promoted migration out of proliferative zones and into the differentiating zone (78.9±13.5 versus 22.3±5.9; P=0.025), as in dorsal cortex.
