Intercellular communication patterns are involved in cell determination in early molluscan development.

The formation of specialized intercellular junctions, allowing the passage of low-molecular weight regulatory molecules, has been considered as a possible mechanism for regulating embryonic development. No direct evidence for this concept has been found in early development. In the mollusc Pattella vulgata it was demonstrated that cell positioning and specific cellular interactions are key factors in the control of early development. We have now investigated the pattern of intercellular communication during early development of this embryo by intracellular iontophoresis of the fluorescent dye Lucifer Yellow CH. We demonstrate that the formation of regional- and temporal-specific cell-to-cell coupling is correlated with the determination of the mesentoblast--the stem cell of the mesoderm--and the establishment of dorso-ventral polarity.