Fig. 8.

DiI labelling of the Xenopus occipital lateral mesoderm. (A, B) Lateral views of Xenopus laevis transgenic cardiac actin:GFP embryos, rostral to the left, dorsal to the top. (Bi) Section of the embryo shown in (B) along the plane indicated in (B), dorsal to the right, medial to the top. (A) DiI-labelling (arrowhead) of the occipital lateral mesoderm next to the 1st somite (as identified by its green fluorescence) at st 20. (B, Bi) Three days later, the labelled lateral mesoderm has expanded in a ventral–rostral direction, surrounding the pharyngeal arches and heading towards the floor of the arches (arrowheads) as previously seen for the chicken. Abbreviations: ect, surface ectoderm; end, endoderm; ht, heart; and lm, lateral mesoderm.