The reconstitution of functional sponges from aggregates, some built from non-fractionated suspensions, others from purified archaeocytes, has been studied using electron microscopy in process of time.The reorganization of aggregates made from complete suspensions mainly consists in a gathering of cells keeping their initial differentiation into functional structures. During restructuration, cellular debris resulting from dissociation and surnumerary healthy cells are phagocytized by archaeocytes.The evolution of archaeocyte aggregates points out the totipotency of these cells, since they appear to be able to differentiate into all sponge cell types. Nevertheless, the anomalies appearing during the sponge reconstitution, which mainly consist in a cell type population ratio desequilibrium, suggest that some morphogenetic regulation mechanisms are lost
