[Thermal-temporal patterns and temporal program of development of poikilothermic animals in the light of the data obtained using dimensionless criteria of duration of development (tau(n)/tau(0))]. / Temperaturno-vremennye zakonomernosti i vremennaia programma individual'nogo razvitiia poikilotermnykh zhivotnykh, kak oni predstavliaiutsia v svete dannykh, poluchennykh s pomoshch'iu bezrazmernykh kriteriiev prodolzhitel'nosti razvitiia (tau(n)/tau(0)).

An attempt was undertaken to generalize and interpret the data on thermal-temporal patterns of development of the poikilothermic animals obtained using relative criteria of development duration.

Maturation of Rana temporaria and Acipenser stellatus oocytes induced by the cytoplasm of embryos at different cell cycle phases and at different stages of cleavage and blastulation.

Experiments involving injections of cytoplasm from the cleaving embryos of Rana temporaria and Acipenser stellatus into fully grown oocytes of the same species and of Xenopus laevis, show that at all mitotic phases, and throughout the period of synchronous cleavage divisions, the cytoplasm is characterized by high activity of the germinal vesicle breakdown factor. This activity decreases during nuclear division desynchronization and drops sharply after the mitotic index fall upon blastulation. Aside from germinal vesicle breakdown in the oocytes, the A. stellatus embryos' cytoplasm also induces development of a cortical reaction capacity.

A study of the properties, morphogenetic potencies and prospective fate of outer and inner layers of ectodermal and chordamesodermal regions during gastrulation, in various Anuran amphibians.

In both the ectodermal and the chordamesodermal regions of Anuran embryos, the outer layer of cells possesses epithelial properties and has the same restricted morphogenetic potencies. It is thus interchangeable between the regions, capable of epiboly and, when underlain by notochord material, of the formation of bottle-shaped cells as at the blastoporal groove, and invagination. When taken from the chordamesoderm region, this outer layer has no inducing effect on the ectoderm of the early gastrula. In normal development the outer layer of the neural plate takes an active part in forming the neural tube cavity. It gives rise to the neuroepithelial roof of the diencephalon and medulla oblongata and, when underlain by neuroblasts that develop from the inner cell layers, to ependymal cells of the brain wall. The outer layer of the notochord material is included in the epithelial layer underlying the roof of the gastrocoel - the hypochordal plate. The inner layers of these regions consist of loosely arranged cells and normally have no epithelial properties although, when taken from the ectoderm region, they may acquire such properties upon long-term contact with the environment. However they have wide morphogenetic potencies; the differences in these potencies between cells taken from the various presumptive regions being less than the differences between outer and inner cell layers in each region. Maps are provided which show the arrangement of presumptive rudiments in the ectoderm and chordamesoderm on sagittal sections through Bombina bombina embryos in early and late gastrulation.