ИСТИНА

It is well known that sponges have unusually high regenerative capacities, which are often associated with their flexibility of tissue organization and high dynamics of cell differentiation. In order to reveal the diversity of morphogenesis and cellular mechanisms involved in the regenerative processes in Porifera, we undertook a detailed comparative study of the regeneration of a number of sponges from phylogenetically distant taxa, differing in anatomical and histological organization. The objects of this project were sponges from the classes Demospongiae, Homoscleromorpha and Calcarea, possessing leuconoid, sycoidoid and asconoid types of the aquiferous system, as well as different degrees of epithelial development. The main mechanism of regeneration of leuconoid Demospongiae is the epithelio-mesenchymal transformation involving the polypotent cells – archaeocytes and choanocytes. The basis for the regeneration of leuconoid Homoscleromorpha and syconoid and asconoid Calcarea is epithelial morphogenesis and transdifferentiation of cells. Regeneration of asconoid Calcarea is a rare example of "pure" morphallaxis. We have shown that the morphogenetic processes revealed in sponges are as complex and diverse as in other higher animals. Thus, sponges can be a source of important information that will allow us to better understand the early evolution of the molecular and cellular mechanisms of morphogenesis in animals. Financial support by Russian Foundation of Basic Research №16-04-00084 and the Russian Science Foundation №17-14-01089 is gratefully acknowledged.