Fig. 4. Ectopic formation of ECN and LRN caused by dominant-negative form of cadherins. (A-D) Dorsal (A,C) and ventral (B,D) views of E18.5 hindbrains (outlined) labelled by electroporation of pCAG-Venus (A,B) and a mixture of pCAG-Venus and pCAG-EGFP-Ncad(t) (C,D). Although control plasmid (Venus) did not affect nucleogenesis of ECN (A) and LRN (B), EGFP-Ncad(t) caused an increase in the size of ipsilateral aggregates (arrowheads in D). Asterisks indicate the labelled side. Rostral is towards the left. Areas outlined in lower panels of A-D correspond to the region shown in the upper panels. (E,F) Localization of EGFP-Ncad(t)-transfected cells (left panel) and Mbh2 signal (middle panel) in ipsilateral (E) and contralateral (F) LRN on transverse section of an E18.5 mouse. Many labelled cells were found in the ipsilateral but not in the contralateral LRN. Neurons in ectopic (ipsilateral) LRN (eLRN) expressed Mbh2 and were intermingled with untransfected LRN neurons (Venus^-/Mbh2⁺) (right panel of E). Each of the three panels in E and F shows the same field. Insets in E are higher-magnification views of the area outlined in the left panel. eECN, ectopic ECN; eLRN, ectopic LRN. Scale bar: in D, 1mm for A-D; in F, 200 µm for E,F, and 50 µm for insets of E.