Fig. 6. Expression of Bb.ß-catenin and Bb2C in the early neurula. Embryos were double-stained for Bb.ß-catenin (A,C) and Bb2C (B,D). (A,B) Dorsal surface view of a stage N1 embryo at the same focal plane. Anterior is to the upper left. The epidermal ectoderm (Ep) has started to spread over the neural plate (Np). Staining for Bb2C yielded no specific signal in the epidermal ectoderm or the neural plate. (C,D) Internal view of a stage N1 embryo at the same focal plane. Anterior is to the lower left. The mesendodermal cell layer is undergoing somitogenesis (arrows). Since the observed embryo is compressed, the apical surfaces of some of the ventrally located, prospective endodermal cells are also in focus. Bb2C and Bb.ß-catenins were detected at the apical zones of the lateral surfaces of the mesendodermal cells (arrowheads). The strongest signals were detected at the blastopore region (Bp). Scale bar: 20 µm.