[DNA synthesis and content in the macrophage nuclei of normal mice, during carcinogenesis and during the administration of retinoids to the animals].

It has been found that nearly 50% of the lymph node and spleen macrophages (MP) of the CBA line mice contain DNA at levels superior to the diploid value (H2c--H4c in mononuclear MP, and up to H16c among polynuclear ones, the latter comprising 2.5-9.0% of the whole MP population).

[Macrophage activation in the immune response].

In inbred white rats, immunized with sheep erythrocytes, contents and phagocytic activity of the spleen and pulmonary macrophages have been studied on the 3d, 4th, 5th, 6th, 7th, 11th, 14th and 20th days of the experiment in the light, scanning and transmissive electron microscope, as well as the effect of the cells mentioned on proliferation of lymphoid elements. Maximal phagocytic activity of the splenic and alveolar macrophages is observed on the 7th day of the experiment. At the same time, certain drop in the lymphoid cells proliferation takes place.

[Effect of retinoids on rat spleen].

It has been shown in experiments on Wistar male rats with the use of light and electron microscopy and morphometry that a single intraperitoneal injection of high doses of all-trans-methylretinoate and methyl-7,8- dihydroretinoate leads to an increase in the spleen weight, the appearance in the spleen of red cells changed in the shape, activation of phagocytic intensity of macrophages, intercellular interaction, lymphocyte proliferation and formation of new lymph follicles.

[Antitumor and toxic properties of retinoid C15].

A study was made of antitumor and toxic properties of retinoid C15 which has some characteristic structural features of retinoic acid natural metabolites; such as ethyl-2E, 4E-3-methyl-5-/2,6-dimethyl-6-ethoxycarbonyl-/3-oxo-1-cyclohexene-1-yl/-2,4-pentadienoate. The substance inhibited the growth of transplantable tumors of the uterine cervix. Lewis carcinoma and rumen cancer.

[Age and features of lymphoid cells after antigenic stimulation].

T- and B-populations of lymphocytes from the thymus, spleen and mesenteric lymph nodes have been studied. Rabbits of various age were immunized intravenously with suspension of 20 . 10 g/kg sheep erythrocytes.