As a result of complex study of lymphocyte-like cells which arise in the regenerating bone marrow of sublethally irradiated mice, it was established that: (1) X-cells precipitate in the 2nd and, partially, 3rd fractions of the albumin gradient, i. e. in the same fractions as the stem cells of intact animals; (2) X-cells do not belong to polypotent hemopoietic stem cells; (3) X-cells belong to B-lymphocytes, i. e. to thymus-independent lymphocytes.

The distribution of total RNA and its individual fractions in two regions of Acetabularia mediterranea stem during regeneration was investigated. During regeneration of both the nuclear and enucleated cells, RNA concentration increases in the cytoplasm of growth zone whereas it changes insignificantly in the central stem region. A study of the qualitative RNA composition in the same stem regions has shown that during regeneration high molecular weight RNA fractions (main peaks - 0,56-10(6) and 1.04-10(6) Dalton) are found in the growth zone and are practically absent from the central cell region. Low molecular weight RNA (supposedly, tRNA and products of RNA destruction) are present in both the cell regions under study.

The author studied substances related to acetylcholine metabolism (acetylcholinesterase, non-specific acetylcholinesterase, SH, SS-groups, histidine, Ca) using histochemical methods. There was an increase in the intensity of reactions on SH-groups and Ca, and a rise in the staining degree on SS-groups and acetylcholinesterase in the subconvulsive phase of the stroke. These shifts were more significant in the brain stem. A generalization of convulsive strokes intensifies the given changes and causes an increase of the intensity of the reactions on histidine after the end of the stroke (after 1, 3, 6, 24, 48 and 72 hours). A normalization of the studied reactions happens at different times in the different brain areas and does not end completely even 72 hours following discontinuance of the convulsions. The author comes to the conclusion that the acetylcholine metabolism is inhibited during the covulsive stroke.

Adult mice of C57BL/6, CBA (CBA X C57BL/6) F1, (CBA X C57BL/6) F2, F1 X CBA and F1 X C57BL/6 strains were lethally irradiated and reconstituted with a constant dose of 3-10(5) C57BL/6 bone marrow cells. At the 9th day after the bone marrow transplantation the colony count was performed in spleen of irradiated recipients. In the spleen of F1, CBA and C57BL/6 mice were registered low (0--8, intermediate (6--18) and high (22-40) numbers of colonies respectively. The segregation ratios in F2 progeny were close to 2 (low): 1(intermediate): 1(high). The segregation ratios in backcross (F1 X CBA) were close to 1(low): 1(intermediate)numbers of colonies. Backcrosses (F1 X C57BL/6) were distributed to low and high numbers of colonies with the ratio 1:1. The number of spleen colonies of males and females was the same in all segregating progeny. The results of hybrid analysis suggest that a single pair of allelic genes is involved in genetic control of allogenic inhibition, and that the resistance (manifestation of inhibition) to C57BL/6 stem cells is conferred by the dominant allele.