X-ray microanalytical studies on cryofixed blood cells of the ascidian Phallusia mammillata. I. Elemental composition of morula cells.

Cryofixed blood morula cells of Phallusia mammillata (Cuvier), which are considered to be vanadium-accumulating cells, were examined by X-ray microanalysis using STEM (scanning transmission electron microscopy) and SEM (scanning electron microscopy). It is thought that cryopreparation preserves the native distribution of diffusible elements such as sodium, chlorine, and potassium, and prevents the displacement of vanadium, all of which may occur during conventional preparation. The results show that morula cell globules contain a large amount of sulphur and chlorine, and some sodium, magnesium, bromium and potassium, but very little or no vanadium.