Fig. 6.

BSE image (white) and calcium EDS map (red) of a fixed and sliced embryo taken with the airSEM. (A) Whole embryo, with calcium EDS map (red) and BSE signal (white) superimposed. The spicule is marked with an arrow, and the membrane enveloping the embryo is marked with arrowheads. (B) Enlargement of the square-labeled area in A, containing a part of the spicule (arrow) and cell group (arrowhead); BSE image. (C) The same region as in B, with calcium EDS map (red) superimposed. EDS quantitative analysis of the marked areas is presented in Table 1. C, cell group; S, spicule.