ИСТИНА

There are many hypothesis proposed to explain mechanisms of morphogenesis regulation in different organisms during their development or regeneration. Among them two main groups can be distinguished. The first one rests on the assumption of morphogen gradients. The second group considers the morphogenesis as self-organising processes. The hypothesis proposed by Beloussov (1975, 1981, 1995, 1996), belonging to the second group, asserts that the mechanical interactions within the rudiment regulate morphogenesis (based on growth pulsation) in thecate hydroids: contraction/extension forces in epithelial layers, changes in the geometry of the rudiment, development in the direction of mechanically stable states. In the present work we experimentally tested the hypothesis of Beloussov (1981; Beloussov et al., 1993, 2003), that in colonial hydroid Dynamena pumila the partitioning of the shoot tip into three rudiments is interconnected with increasing of its size. We experimentally limited increasing of the shoot apex diameter expecting that the morphogenetic cycle will end by subdivision of the shoot tip into the fewer rudiments. Our results testify against the idea that only the mechanical interactions regulate internode morphogenesis in D. pumila. There is a certain morphogenetic programme independent from physical parameters of the tissue.