Mosaic vs regulative development spectrum

Mosaic and regulative development are the two ends of a spectrum of cell fate specification in animal embryos. In mosaic (autonomous) development, a cell’s fate follows from maternal determinants that the egg localizes and that dividing cells pass to their daughters. In regulative (conditional) development, a cell’s fate follows from signals exchanged with neighboring cells after each division. The modes separate cleanly when cells are moved or destroyed: a strictly mosaic embryo that loses a cell leaves the corresponding structure missing, while a strictly regulative embryo redistributes fates and builds a complete, smaller animal. Most embryos combine