[Spatial-temporal dynamics of morphogenetic blastoderm potencies in early embryogenesis of the loach].

The degree of differentiation of axial structures (notochord, neuroectoderm, and somites) in 24-hour explants (a total of 380) of the loach embryonic blastoderm was determined on histological sections according to a developed scale of estimates. Before the beginning of epiboly, axial structures were formed only from fragments of the dorsal sector of the blastoderm marginal zone. Its other sectors acquired the capacity of forming axial structure only with the beginning of epiboly, as the germ ring was formed in the marginal zone, unlike the cells outside the germ ring.

[Role of cooperative cell movements and mechano-geometric constrains in patterning of axial rudiments in Xenopus laevis embryos].

The role of cooperative cell movements has been explored in establishment of regular segregation of the marginal zone of Xenopus laevis embryos into the main axial rudiments: notochord, somites and neural tissue. For this purpose, the following operations were performed at the late blastula-early gastrula stages: (1) isolation of marginal zones, (2) addition of the ventral zone fragments to the marginal zones, (3) dissection of isolated marginal zones along either ventral (a) or dorsal (b) midlines, (4) immediate retransplantation of excised fragments of the suprablastoporal area to the same places without rotation or after 90 degrees rotation, (5) pi-shaped separation of the suprablastoporal area either anteriorly or posteriorly. In experiments 1, 4, and 5, lateromedial convergent cell movements and differentiation of the axial rudiments were suppressed.

[Kinetics of the reaction of yolk cell surface in the loach to puncture and mechanic deformation].

Circumferential and radial components of the yolk cell surface movements were measured in the loach embryos at the late blastula stage within 40-50 min after puncture or indentation by an obliquely directed glass rod. The yolk cell surface was preliminarily marked by coal particles. It was shown that even closely located regions of the surface differed markedly in the rate and direction of their movements.

[Structurization of cortical layer of loach yolk cell after wounding as a "minimal" model of morphogenesis].

Structural rearrangements of the yolk cell surface were studied in loach embryos using SEM and TEM, which take place within 30 min after a point-like puncture at the late blastula stage. The effects of sucking off or addition of a part of yolk, lowered temperature, and absence of Ca2+ on structurization were studied. Around the area of puncture, the yolk granules were submerged, the number of vesicles increased, and numerous membrane folds were formed.

[The loach--the object of experimental embryologic research in the Department of Embryology].

This paper provides a history of research at the Department of Embryology on the teleostean loach fish Misgurnus fossilis L. as a model. The use of the loach in education is briefly described.