Fig. 7. ATBF1 expression at the GE and the isthmus in a sagittal section of E14.5 rat brain. (A) ATBF1 is expressed at the GE; in the cytoplasm of the VZ; weakly in the nucleus of the SVZ; strongly in the nucleus of the DF; absent from the white matter (W). (A1-A3) Higher magnification of the numbered areas in A. (B) Fibronectin is expressed on the surface of the ventricle, sparsely in the SVZ, in intercellular space of the DF and strongly in the white matter (W). (B1-B3) Higher magnification of the numbered areas in B. (C) Expression pattern of fibronectin at the isthmus. (C1) Higher magnification of the framed area of C. There are two regions: one has a high cell density (C1, region I), the other has a lower cell density (C1, region II). (A,B,C,C1) DAB and Hematoxylin counterstaining. BrdU (D,D1,D2), ATBF1 (E,E1,E2) and merged images of BrdU and ATBF1 (F,F1,F2). BrdU labeling indicates rapid proliferation on the ventricular side (D1) and suppression of the cell cycle on the dorsal side (D2). ATBF1 expression is present in the cytoplasm (E1) and the nucleus (E2).