Research into the activity of the enzymes invertase, gamma-amylase, alkaline phosphatase in the macrocolonies of the rat small intestine has shown that each macrocolony has stringently individual functional properties and the predominance of one of the enzymes. The data have been also obtained, indicating different rate of lysin and leucin absorption by the macrocolony epithelium of the small intestine. The results prove the existence of a definite functional differentiation of epitheliocytes (macrocolonies) arising from the same stem cell of the intestinal epithelium.

By means of the horseradish peroxidase (HP) retrograde axonal transport method localization of HP-labelled neurons in the forebrain cortex making projections on some somatic (motor and sensory) spinal and truncal centers, as well as on the retucular formation, substantia nigra and hypothalamus has been studied. Certain peculiarities in localization of the neurons giving origin to various fibre systems in the forebrain cortex have been revealed. Differences are especially noticeable in the area of sulcus chiasmaticus. Only when HP is infected into the spinal cord there is nearly no labelled neurons in the orbital-frontal cortex, while if the enzyme is injected into other structures studied HP-positive cells are revealed in this cortical area. Numerous labelled neurons are noted in the orbital-frontal cortex when HP is injected into the reticular formation and nuclei of the midbrain--the red nucleus and substantia nigra. In the lateal sulcus area HP-positive neurons are revealed when the enzyme is injected into the spinal cord and substantia nigra. Neurons giving origin to the fibre systems running to the spinal cord and to a number of subcortical formations are situated in the layer V. Cortico-hypothalamic neurons, that localized not only in the layer V, but also in the layers III--IV of the frontal cortex and in the layer VI of the orbital cortex--in the presylvian fissure are, make the exception to the rule.

Acute hemorrhage of varying severity was produced in (CBA x C57BL/6)F1 hybrids. Then it was followed by the induced systemic graft-versus-host reaction (GVHR). The increased intensity of the hemorrhage made the course of the systemic GVNR more severe. The 10th day after GVHR induction no significant differences were found in the peripheral blood of experimental or control animals. However, the hybrids demonstrated a significant rise in the number of exogenic stem cells in the spleens during hemopoietic regeneration and diminution of the immunocompetence of splenic T cells.

Colony-forming capacity of quail yolk sac and embryo was studied after 48 hours of incubation, and that of yolk sac, limb bud and heart germ of the quail embryo after 60 hours of incubation. The concentration of colony-forming units (CFUm) of the 48-hour embryo was shown to be one hundred times higher than that of the yolk sac both after 48 and 60 hours of incubation. The concentration of CFUm in the embryonic limb buds and heart germ after 60 hours of incubation was approximately the same and comparable to the concentration of CFUm in the 48-hour embryo.

During the stepped rapid training of mice for hypoxia the number of colony-forming units in the blood and bone marrow increases and that in the spleen falls down. In acute hypoxic hypoxia there is an enhancement of the migration of stem hemopoietic cells and B-lymphocytes from the bone marrow and T-lymphocytes from the thymus.

On the basis of a mathematical model imitating known properties of stem blood-forming cells regeneration of these cells was studied under the conditions of antitumor therapy depending on the regime of cytostatics introduction. Metotraxat and vinblastin preparations taken as an example, a principal possibility for theoretical analysis of toxic influence of cytotoxic therapy on stem hemopoietic cells was shown as well as modification of the schemes of introduction of antitumor preparations for decreasing their suppressing effect on hemopoiesis. Possible application of kinetic modelling of regeneration of the pool of stem hemopoietic cells for preclinical selection of the schemes of antitumor therapy, taking into account their effect on the hemopoiteic system is discussed.

Radioimmunological method was applied to the study of progesteron and 17 beta-estradiol profiles in the peripheral blood plasma of pregnant mice from the time of the zygote formation (the 1st day of gestation) to the blastocyst implantation (the 5th day of gestation). The peak of a progesteron concentration in the plasma and the onset of reduction in the 17 beta-estradiol concentration were noted in the evening of the 3rd day of pregnancy. From this period there was a fall in the 17 beta-estradiol and progesterone content in the blood plasma. In the evening of the 3rd day of pregnancy the 14-18-cell embryos passed from the oviduct into the uterine cornu. The role played by the embryo in changes of the maternal hormonal status is discussed.

The data on the control of ontogenetic hemoglobin type synthesis were analyzed in normal and pathological human and animal organisms. The assumption is made that such control depends on the level of erythroid cell differentiation and erythropoetic factors activity. The latters act as a trigger in switching of qualitative hemoglobin production.

M. arthritidis is known to enhance the leukemogenic effect of Rauscher leukemia virus in mice of different strains. As we have found earlier, M. arthritidis enhanced endogenous colony formation in irradiated mice. In this paper we made an attempt to establish a connection between these two phenomena. The mixed inoculation of BALB/c mice with M. arthritidis and Rauscher leukemia virus produced a great increase in the number of endogenous colonies as compared with the effect of mycoplasmas alone, while Rauscher leukemia virus did not enhance the number of colonies. When injected into mice a day before their lethal irradiation, M. arthritidis was shown to increase the survival of mice within 30 days following irradiation. We tried to determine the possible mechanism of the effect of M. arthritidis on hemopoiesis. Our findings led us to the conclusion that the mycoplasmas had no influence on the splenic microenvironment and did not increase the migration of the surviving stem cells to the spleen. It is conceivable that M. arthritidis acts not on the pluripotent stem cells, but rather on the committed precursor cells. If so, the mechanism responsible for the enhancing effect of mycoplasmas on the development of Rauscher leukemia and endogenous colony formation resides possibly in the capacity of M. arthritidis to increase the number and/or sensitivity of target cells to the virus.