The small cells of coelomic fluid and coelomic epithelium isolated from starfish <Emphasis Type="Italic">Asterias rubens</Emphasis> and <Emphasis Type="Italic">Asterias amurensis</Emphasis> (Echinodermata: Asteroidea): Comparative analysis of cell morphology and proliferative activity in vivo and in vitro

Earlier we revealed the probable candidates for the role of Asteroidea stem cells in the starfish Asterias rubens L., small coelomic epithelial cells (SECs-1) with a high nuclear–cytoplasmic ratio that were able to proliferate in vivo and in vitro. To check the existence of a similar cell type in other members of Asteroidea, the small cells in suspensions of coelomic fluid (CF) and coelomic epithelium (CE) of A. amurensis were analyzed with respect to their morphology and proportion in the total cell pool. The morphology of proliferating cells and the proliferative activity of CF and CE cells in vivo and in vitro were studied. The small cells with parameters identical to those of A. rubens SECs-1, were found both in CF and CE of related species. The subpopulation of weakly attached CE cells, highly enriched with SECs-1, was detected. These cells were able to migrate from CE and to proliferate in vivo and in vitro. Additionally, large proliferating cells were described in both starfish. The dynamics of proliferative activity in primary cell cultures of these starfish had some distinctions. Moreover, for the first time, the formation of “crystals”, the potential centres of spiculogenesis, was observed in primary culture of A. amurensis CE cells. The data prove that SECs may fulfil the common functions in two members of Asteroidea.