Fig. 3

Sall expression in C. fornicata. In situ hybridization of sall mRNA in embryos from 16-cell stage to organogenesis. The distribution of labeled mRNA is shown by the dark blue staining. In all images orientation is indicated at the bottom left corner of each panel. Scale bar at the bottom right corner equals 40 µm. Yellow arrowhead indicates the blastopore/stomodeum. a, c 16- and 24-cell stage embryos, respectively. mRNA is expressed in the macromeres. The lighter colored nuclei are labeled with Hoechst (blue). b, d Schematic representation of 16- and 24-cell embryos, respectively, in animal view (modified from Henry et al., [47]). Capital letters indicate the macromeres and lowercase letters the micromeres. e–j′ Localization of sall mRNA in blastula stage. e–e′, j–j′ Bright-field and fluorescent Hoechst-labeled corresponding images. f–i Lateral view of each quadrant. Green and red arrowheads indicate stained reference cells in quadrants C and A, respectively, in different views. q quadrant, A animal pole, V vegetal pole. k–n′ Localization of sall mRNA in gastrula stage. Each bright-field image has a corresponding fluorescent Hoechst-labeled image on the right. o–q′ Localization of sall mRNA in organogenesis. o, o′ Bright-field and fluorescent Hoechst-labeled corresponding images. p Bright-field right view. The blue arrow indicates the asymmetric patch of expression present in this side. q Bright-field left view. A: anterior; P: posterior; V: ventral; D: dorsal; R: right; L: left