[Visualization of the cytoplasmic segregation structure by using computed microscopy]. / Vizualizatsiia segregatsionnoi struktury tsitoplazmy s pomoshch'iu komp'iuternoi mikroskopii.

Cytoplasm organella segregation accompanies virtually all the changes occuring in embryonic and differentiated cells. The general scheme of mapping spatial distribution of cytoplasm texture parameters, realized using computed microscope LEITZ-T.A.S., allowed the imaging of geometrical relationship between yolk granules in the Rana Temporaria fertilized egg. The development of dorsoventral polarity in amphibian embryos was shown to be related to shape and location asymmetry of cytoplasm area containing clusters of yolk granules.

[Dynamics of the redistribution of pigment granules in the dermal melanophores of anuran amphibians. 1. Dispersion]. / Dinamika pereraspredeleniia pigmentnykh granul v dermal'nykh melanoforakh beskhvostykh amfibii. 1. Dispersiia.

The dispersion of melanosomes in the dermal melanophores of the Xenopus laevis larvae has been studied by time--lapse cinematography. The process began with the appearance of distally directed melanosome flows in the cell cytoplasm. During the subsequent migration of pigment granules, the flows branched forming branches of the 2nd and higher orders. The whole cytoplasm became filled with a layer of melanosomes. During the dispersion, the movement of melanosomes in a flow is replaced by their dispersion all over the cytoplasm; these processes alternated. In the peripheral part of the cell devoid of melanosomes, membrane vesicles appeared and the cytoplasm was distinctly divided into ecto- and endoplasm. The ectoplasm contained numerous microfilaments and single microtubules, the endoplasm did not contain any cell organelles, except single electron-dense melanosomes. The active role of plasma membrane in the intracellular movement of melanin granules is suggested.

[Structure of the morphogenetic movements of gastrulation in Anura. I. Destabilization of ooplasmic segregation and cleavage under the action of clinostatic rotation]. / Struktura morfogeneticheskikh dvizhenii gastruliatsii u beskhvostykh amfibii. Soobshchenie I. Destabilizatsiia ooplazmaticheskoi segregatsii i drobleniia pod deistviem klinostatirovaniia.

The yolk segregation in the developing Rana temporaria egg was studied both in vivo and under the effect of clinostate rotation, i. e. slow rotation around the horizontal axis imitating the state of weightlessness. From the moment of fertilization and during the whole period of cleavage the yolk was shown to subdivide succesively in distinct phases which differ by the characteristic value of yolk granules. During the normal development, in spite of the marked variability of form and mutual position of phases, the main elements of their animal-vegetative order are preserved. Under the effect of clinostate rotation the process of normal segregation becomes destabilized and variations in the egg structure are expressed by the beginning of gastrulation in the diversity of variants of distribution of the cellular material competent to different morphogenetic movements.

[Structure of the morphogenetic movements of gastrulation in Anura. II. The elementary morphogenetic processes]. / Struktura morfogeneticheskikh dvizhenii gastruliatsii u beskhvostykh amfibii. Soobshchenie II. Elementarnye morfogeneticheskie protsessy.

The clinostate rotation causes a wide range of gastrulation abnormalities in the Anura. A special investigation has shown that all gastrulation variants may be represented as various spatial-temporal compositions of the same morphogenetic processes isolated by means of formal experimental procedure. These processes are structurally stable rearrangements of tissue morphology and are spread in the tissue as a wave embracing more and more cells. The change of one local morphology for another may proceed either in the form of "shock wave", a moving distinct border between the cells already switched and not yet switched to the new automorphous movement, or in the form of "deployment" when the transition from one local morphology to another is continuously deployed in space.

[Patterns of mechanical stress at the successive stages of early development of frog]. / Arkhitektura mekhanicheskikh napriazhenii na posledovatel'nykh stadiiakh rannego razvitiia liagushki

The immediate relaxation deformations have been studied in the embryonic frog tissues from the late blastula stage till the early tail bud stage. As a result, the maps of mechanical stresses were constructed which were characterized by the existence of distinct tension-lines dissecting the embryonic tissues (cross-lines). A few discrete moments of development were established when new cross-lines formed or the previous ones disappeared; they are separated by the topologically invariant periods of development. The cross-lines play an important role in morphogenesis in that they determine the ways of active cell migration and trace the boundaries between different anlages. The orientation of the cross-lines coincides, as a rule, with the direction of predominant tension of tissues during the preceding topologically invariant period of development.

[Mechanisms of growth and morphogenesis of hydroid polyps as revealed by time lapse microcinematography]. / Mekhanizmy rosta i morfogeneza gidroidnykh polipov po dannym tseitraffernoi mikrokinos'emki

By means of time lapse microcinematography, parameters of growth fluctuations in hydroid polyps Obelia and Dynamena were improved, the pulse pattern of morphogenetic processes was shown, the "antiphase" phenomenon was established in the growth fluctuations of adjacent rudiments of Dynamena. In the phase of rudiment stretching, the length of ectodermal epithelial-muscular cells reduces and their orientation changes, thus leading to the displacement of the whole cellular "column" in the distal direction. In the phase of rudiment partial shortening, endodermal cells loose and lengthen, their internal ends displace in the proximal direction and their external ends slide rapidly in the distal direction with respect to hydrotheca. Changes in the form of rudments arise as a direct mechanical result of periodical contractions of cells densely packed in the epithelial layer. On the basis of these data, morphogenetic processes in hydroid polyps related to the appearance and development of folds and to the rudiment flexures are analyzed.