| Popis: |
Data analysis reveals that cells of most of the metazoans (especially from the phyla Spongia, Placozoa and Cnidaria) at the early stages of morphogenesis demonstrateas amoeboid properties i.e. ability to form pseudopodia, to move by means of pseudopodia and to phagocyte. In different degress these properties could be found at the late stages of embryogenesis and even in adult organisms. Moreover, during gastrulation and blastulation blastomeres is able to form flagellas and than loose them and return to amoeboid activity. These and other facts indicate that both amoeboid and flagellate types of cellular organization are programmed in the genome of metazoan cells, as well as their ability for mutual transformation. It leads to suggestion that ancestors of Metazoa were amoeboflagellates. Anarchic cleavage observed in some invertebrates evidences that separated blastomeres is able to aggregate into the unite embryo due to cytotaxis. Aggregation of artificially separated cells of sponges, trichoplax and cnidaria results in complete recovery of the organism by cytotaxis. Thus, there are reasons to suppose that ability of cell aggregation was inherited by the Metazoan genome from the amoeboflagellate ancestors. Thus amoeboflagellates may be considered as forerunners of Metazoa, i.e. Prometazoa. |
