EUROMEDICA  Hanover 3-4  Juni 2010	Advanced methods of diagnosis, treatment and prophylactics
	European Academy of Natural Sciences, Hanover European Scientific Society, Hanover Berliner Medizinischen Gesellschaft, Berlin

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Study of the mechanism of separate tissues morphogenesis during the embryogenesis, particularly during the transition from one structural level to another, is associated with clarification of the ways of formation of one or another tissue, that has a direct relation to the realization of the morphological diversity in evolution. Meanwhile, as a main driving force of the evolution acts firstly differentiation of the initial cellular components and then cellular mutual contact, which lead to the formation of the different tissues.

Separation of the myoblasts from myotome and their junction in muscle plate and myosymplast is an indicator of the first stage of histogenetic differentiation of the animals` skeletal muscles. In the sequel, initially myotubes, later on primitive and definitive muscular fibres are formed in these myogenic structures because of the complexation of the myofibrillar apparatus. Such a consecutive morphological rearrangement, on the one hand, is repeated differentiation of the myogenic components and on the other hand, is morphofunctional adaptation of the muscle tissues. Besides, each subsequent form rejects the previous form of existence. In the development of skeletal muscles in vertebrate animals caenogenesis or embryonic adaptation is determined, which exists during the specified periods of ontogenesis and later on disappear, that is, definitive muscle fibres are formed. In our opinion, it is correct to subdivide caenogenesis to -cellular (early) and symplastic (late). Within this period cross-striated muscle fibres still are not differentiated histologically, therefore it is not acceptable to name this period as caenogenesis on fibre level.

Let’s have a look at, which histogenetic recapitulations are present in the development of muscle fibres of these animals. Suppose that, differentiation of the muscle fibres consists of stages: mesoderm, somites, myotome, myoblast, muscular plates, myosymplast, muscular tubes, primitive (young) muscular fibres, definitive muscular fibres. First of them – formation of the third embryonic layer, which is formed by teloblastic (in archaeostomatous) or by onterosol way. Second – emergence of somites , third – myotomes, fourth – separation of the myoblasts from myotomes, fifth - merging of myoblasts into the muscular plates, sixth – formation of the myosymplasts, seventh

– formation of muscular tubes and at last, eighth – formation of the definitive muscular fibres. Most of the mycologists subdivide the last-eighth stage into the primitive or young muscular fibres and definitive muscular fibres. Consequently, the eighth recapitulation can be considered as a two-stage.

Not only the fact of historecapitulation`s existence, but also the cases of its infringement has great significance in clarification of the ways of tissues` evolution. Otherwise evolution would not happen. In the development process, on the one hand there has to be conservative inheritance, but on the other hand there must be changeability. Stated transitional moments, periods in differentiation may be example of such infringement.

Above-stated shows the rightness of division of recapitulation into the histogenetic and anatomic directions. As for recapitulation, which is marked by ourselves in the development of skeletal muscles in representatives of different categories of vertebrate animals, it persuasively reveals the presence of first of them – histogenetic recapitulation in embryonic histogenesis.