Fig. 5. Explant culture experiment: control experiment. (A) Two types of explants were generated, one comprising the lateral PSM (left explant) and the other containing the corresponding medial PSM, the axial structures and the control PSM (right explant). In order to ensure that the PSM tissue was being subdivided into equivalent medial and lateral halves, some explants were randomly taken, immediately fixed and hybridised either with probes for Delta-1 (B) or with BMP-4 (C). These control experiments show that the Delta-1 domain of expression is longitudinally subdivided into two halves. In the BMP-4 hybridised explant, a thin domain negative to this gene is present corresponding to the lateral PSM tissue. Scale bar: 250 µm.
