Basic morphogenetic processes in Hydrozoa and their evolutionary implications: an exercise in rational taxonomy

Beloussov, L. V.

doi:10.1007/bf00026444

Cited by 5 publications

(3 citation statements)

References 6 publications

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“…They can be distinguished most clearly within the growing tip and in the coenosarc just proximal to it ( Figure 7H ). These are the parts of the stolon that permanently undergo active contraction and pulsation (Wyttenbach, 1968 ; Beloussov, 1973 , 1991 ; Kosevich, 2006 ).…”

Section: Resultsmentioning

confidence: 99%

Ultrastructural and immunocytochemical evidence of a colonial nervous system in hydroids

Kosevich

2023

Front. Neural Circuits

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BackgroundAs the sister group to all Bilateria, representatives of the phylum Cnidaria (sea anemones, corals, jellyfishes, and hydroids) possess a recognizable and well-developed nervous system and have attracted considerable attention over the years from neurobiologists and evo-devo researchers. Despite a long history of nervous system investigation in Cnidaria, most studies have been performed on unitary organisms. However, the majority of cnidarians are colonial (modular) organisms with unique and specific features of development and function. Nevertheless, data on the nervous system in colonial cnidarians are scarce. Within hydrozoans (Hydrozoa and Cnidaria), a structurally "simple" nervous system has been described for Hydra and zooids of several colonial species. A more complex organization of the nervous system, closely related to the animals' motile mode of life, has been shown for the medusa stage and a few siphonophores. Direct evidence of a colonial nervous system interconnecting zooids of a hydrozoan colony has been obtained only for two species, while it has been stated that in other studied species, the coenosarc lacks nerves.MethodsIn the present study, the presence of a nervous system in the coenosarc of three species of colonial hydroids - the athecate Clava multicornis, and thecate Dynamena pumila and Obelia longissima - was studied based on immunocytochemical and ultrastructural investigations.ResultsConfocal scanning laser microscopy revealed a loose system composed of delicate, mostly bipolar, neurons visualized using a combination of anti-tyrosinated and anti-acetylated a-tubulin antibodies, as well as anti-RF-amide antibodies. Only ganglion nerve cells were observed. The neurites were found in the growing stolon tips close to the tip apex. Ultrastructural data confirmed the presence of neurons in the coenosarc epidermis of all the studied species. In the coenosarc, the neurons and their processes were found to settle on the mesoglea, and the muscle processes were found to overlay the nerve cells. Some of the neurites were found to run within the mesoglea.DiscussionBased on the findings, the possible role of the colonial nervous system in sessile hydroids is discussed.

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Section: Resultsmentioning

confidence: 99%

Ultrastructural and immunocytochemical evidence of a colonial nervous system in hydroids

Kosevich

2023

Front. Neural Circuits

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“…The consequences of such a phenomenon are discussed in detail in the works by Beloussov (1975Beloussov ( , 1991. But the transition toward subdivision of the growth zone into two rudiments opens a new phase in the evolution of shoot morphogenesis and structure.…”

Section: Arrangement Of Growth Zones Within the Colonymentioning

confidence: 99%

“…In this paper we took into account the series of papers by Berrill (1949aBerrill ( , b, c, 1950, and 'the theory of biological (embryonic) field' by Gurwitsch (1922) and his followers (Beloussov & Ostromova, 1969;Beloussov et al, 1972;Beloussov & Dorfman, 1974), including the only papers of their kind by Beloussov (1975Beloussov ( , 1991 on the 'parametric system of hydroids'. However, such works are still few in number, so the method of morphogenetic analysis in classification of forms remains poorly developed.…”

Section: Introductionmentioning

confidence: 99%

Morphogenetic evolution of hydroid colony pattern

Marfenin

Kosevich

2004

Hydrobiologia

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A scheme of evolution of hydrozoan colony pattern is proposed based upon the consideration of macromorphogenesis. Four main processes play decisive roles: (1) hard skeleton formation by soft tissues, (2) changes in duration of the growth phase relative to the transition to differentiation in interdependent zones of growth, (3) ratio in growth rates between adjacent zones of growth within the rudiment, the shoot, or the whole colony, and (4) spatial relationships among growth zones. The main tendency in morphological evolution of the hydroids is an increasing integration of the colony as revealed by increasing complexity of its structure. That is from a temporary colony towards the permanent one with highly organised shoots, as hydranths and branches are localised in a strictly arranged manner. An analysis of diverse data allows one to state that the main morphogenetic mechanism of increasing complexity in the hydroid colony is convergence, then fusion, of adjacent growth zones, a variant of heterochrony.

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Basis of ontogenetic and evolutionary transformations of thecate hydroids

Kosevich

2015

Paleontol. J.

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Basic morphogenetic processes in Hydrozoa and their evolutionary implications: an exercise in rational taxonomy

Cited by 5 publications

References 6 publications

Ultrastructural and immunocytochemical evidence of a colonial nervous system in hydroids

Ultrastructural and immunocytochemical evidence of a colonial nervous system in hydroids

Morphogenetic evolution of hydroid colony pattern

Basis of ontogenetic and evolutionary transformations of thecate hydroids

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