Fig. 5.

Calcification from seawater vacuoles labeled with calcein: (A) At the end of a 1-h incubation with the dye (pulse) followed by washing with normal seawater (chase), the labeled outline of the chamber represents the calcification during the pulse incubation. (B) After 24 h of chase, the chamber wall is thicker, and the labeled calcite strip has expanded when the only source for the calcein is the labeled seawater vacuoles. v = vacuoles, in = intracellular, ex = extracellular, w = chamber wall, s = algae symbionts, sc = secondary crystals.