Ultrastructure of the nerve apparatus in the arteries of the brain base has been studied in cats. The structure of peri- and adventitial nerves has been investigated electron microscopically. Three types of efferent axons and four types of synaptic vesicles (small agranular and granular, large granular, large electron opaque vesicles) have been revealed. Vesicle-containing axons in the brain arteries approach the external smooth muscle cells of about 80 nm. Terminal axonal dilatations possessing direct and mediated connections with muscular cells of the middle tunica have been revealed.

The paper contains a clinico-morphological description of a case with late sequelae of treated tubercular meningitis. The patient at 7 years of age had tuberculous meningitis which was treated by suboccipital and endolumbar administration of streptomycin. Following 12 years, epileptical seizures ensued with an eventual gradual weakness in the extremities leading to profound spastic tetraparesis. During the last years of life contractures and stem symptoms developed. The morphological picture was characterized by posttuberculous fibrous leptomeningitis with an extensive internal hydrocephalus, universal sclerosis of the cerebral and spinal vessels, disseminated demyelinization in the spinal cord and brain, a distinct improverishment of the grey matter by ganglionic cells. The result of liquorohemodynamical disorders was a syringolike cavity in the spinal cord. Under the ependima of the laral ventricle calcified cholesteatomas were found, which are considered as complications of suboccipital punctures in administering streptomycin.

The expression of allogenic inhibition was studied when transplanting 10(5) cells of bone marrow of C57BL mice to the lethally irradiated recipients (CBA X C57BL) F1 of different age (2 to 11 months). In the control experiments the bone marrow cells at the same dose were introduced to the lethally irradiated syngenic (C57BL) mice. The most pronounced inhibition of the parental stem cells proliferation was registered in 2 months old recipients F1 (4.7 times), it was somewhat weakened in 3 months old and animal in 4--11 months old recipients (1.1 to 1.8 times). The thymectomy of adult recipients F1 did not eliminate the expression of allogenic inhibition.

The analysis of literature experimental data on cell kinetics of the generating intestinal epithelium of rats and mice suggested the irreversibility of transformation of intestinal epithelium stem cells into non-stem proliferating enterocytes and the ability of the latter for self-reproduction. This property of half-stem enterocytes enabled us to assume that the daughter cells immediately after their appearance are always in the G1-phase of the mother cell mitotic cycle.

A model of functional-morphological organization of epithelium of human normal, hyperplastic, and tumour endometrium is described. The model is based on a hypothesis that a population of stem cells capable of indefinite unlimited self-maintenance exists in normal glandular epithelium of the endometrium. The population of normal stem cells of endometrium epithelium is the source of emergence of differentiated types of epithelial cells among which, according to the model, three cell types can be distinguished: cells sensitive to estradiol alone, cells sensitive to both estradiol and progesteron, and cells sensitive to progesteron alone. The conditions necessary for transition of one cell type to another as well as histochemical characteristics of each of the cell types are described. The model has been used for the analysis of morphological changes developing in hyperplastic processes and cancer of the endometrium as well as for the substantiation of the current schedules for hormone therapy of these diseases.

Resection of 2/3 mass of the pancreas preserving the ducts of the central portion is accompanied in dogs by certain changes in lymph nodes of the small intestine radix mesenterii. The operative trauma is followed by size decrease of the lymph nodes owing to degeneration and migration of lymphocytes. Absorbtion of decay products from the operative wound results in lymphocytic blasttransformation and proliferation. By the end of the first and beginning of the second month of the experiment, certain involution is noted in the lymph nodes. Further regeneration of the pancreatic stem and restoration of the lymph nodes structure develop nearly simultaneously.

Changes of the circadian rhythm of the general numbers of nucleus-containing cells and leucograms of peripheral blood in NZB mice with autoimmune spontaneous hemolytic anemia and in C57BL mice without visible disturbances in the system of immunostructural homeostasis were the most obvious in the white blood in NZB mice: a) disappearance of the circadian rhythm of the general number of nucleus-containing cells in peripheral blood owing to the inversion of circadian rhythm of the absolute number of neutrophiles; b) changes of circadian fluctuations of lymphocytes-neutrophiles ratio. The observed differences in circadian rhythms of hematological indices in NZB and C57BL mice seem to stem from insufficiency of adrenal cortex function and/or changes in functional state of hemopoietic tissue which can occur during the development of autoimmune processes.

The effect of distribution of injected colony-forming units (CFU) in the recipient's organism was studied. The distribution was assessed by the "sedimentation factor" (f) criterion. This factor was found by the number of colonies revealed on histological sections of the spleen and femoral bone marrow in comparison with the number of colonies visible on the surface of the spleen. Macroscopic count of the colonies on the spleen permits, to assess the f value both in the whole spleen volume and in the femoral bone marrow. In this case f value was independent of the character of CFU differentiation. f value could change depending on the physiological condition of CFU population. In irradiation of the bone marrow CFU in a dose of 200, 400 and 600 R f value in the spleen decreased in comparison with control, but remained unchanged in the bone marrow.

Following fractional irradiation of the mouse bone marrow (300 rad in vitro + 300 rad in vivo) the damage of stem hemopoietic cells was more pronounced when the interval between the irradiations was 30 min as compared to five hrs, on account of recovery from sublethal radiation injury (Elkind's repair of radiation damages). In adult thymectomized mice the capability of stem hemopoietic cells to Elkind's repair was sharply deranged 2.5 to 5 months after the operation. This effect of thymectomy was abrogated by the newborn thymus graft.

Tests staged on line-bred mice immunized with sheep erythrocytes brought evidence that cystostasan and iodobenzoteph cut down the number of antibody-forming cells both with the primary and secondary immune response. The maximal effect becomes manifest following introduction of the drugs on the 1--2nd day after immunization of the animals. Iodobenzoteph brings down the number of hemopoietic stem cells colonies while cytostosan leaves them unchanged.