Figure 3

Confocal micrographs and 3D reconstructions of blastula and gastrula stages of Loxosomella sp. "Apical cross patterns" are indicated by white and red lines in D and G. Apical rosette cell nuclei are marked with asterisks in D, E, G, J and vegetal "macromere" quartet cells by double arrowheads in F. Scale bars: 10 μm. A, D, G: Nucleic acid staining (blue). E, F: Nucleic acid (blue) and F-Actin staining (red). J: Nucleic acid staining shown as depth-coded confocal projection. A: vegetal view, D, E, G, J: animal view, F: vegetal view. B, C, H, I, K, L: 3D reconstructions. B, H, K: animal view, C, I, L: lateral view. red: "macromere" quartet (i.e. vegetal) cell nuclei; green: (derivatives of) apical rosette cell nuclei; purple: other cell nuclei. A-C: 36-cell stage. D-F: 43-cell stage. D: Cells surrounding the apical rosette (asterisks) show both, a molluscan- and an annelid-like cross pattern. G-I: 51-cell stage. J-L: Gastrula stage (107 cells). J: Derivatives of apical rosette cells lie in a lower plane than the surrounding cells. K, L: Gastrulation. Vegetal cells (red), blastocoel (arrow).