[Influence of ß - carotene on the spermatogenic epithelium and output dominant lethal muthations in rats under the exposure to hexavalent chromium].

In adult rats exposed to hexavalent chromium (intraperitoneal injection of 0.028; 0.28 and 2.8 mg KCrO(kg bw/ day) during 48 days there is observed the decrease in the intensity of index of spermatogenesis, increase ofspermatids with micronuclei, intensifying of processes peroxidation of lipids in testis, resulted in the increase in the number of the abnormal spermatozoa and of percent of a fetal death. Simultaneous supplementation of ß-carotene in Cr (VI) exposed rats showed the increase of intensity index of spermatogenesis. Morphology of a sperm, intensity of processes peroxidation of lipids in testis and of number of viable embryos was restored.

[Comparative analysis of ionizing radiation and xenobiotics influence on spermatogenic epithelium and dominant lethal mutations output in laboratory animals].

The study covered state of spermatogenic epithelium and dominant lethal mutations output in mice of BALB/c and CBA lines, subjected to total gamma-irradiation and in Wistar rats after intraperitoneal injection of potassium bichromate (K2Cr2,O7) in small and sublethal doses. The BALB/c line mice under low irradiation dose (0.25 Gy) demonstrated stimulation effect on spermatogenic epithelium, but in the CBA line mice no such effect was seen. Both mice lines under irradiation of 0.25 Gy and 1.0 Gy demonstrated increase in pathologic sperm counts and in percentage ofpreimplantation embryonal death. In rats, injection of potassium bichromate in doses of 0.028 mg/kg and 2.8 mg/kg increased number of micronuclear spermatids, larger pathologic sperm counts and percentage of postimplantation deaths. Thus, lower general embryonal deaths under radiation exposure is due to preimplantation embryonal deaths, under exposure to 6-valent chromium--is due to postimplantation losses.

[Morphofunctional analysis of testes and sperm in the assessment of male reproductive success in the bank vole (Clethrionomys glareolus)].

The morphofunctional analysis of testes and sperms in bank vole (Clethrionomys glareolus, Schreber, 1780) from a natural population is carried out to assess the reproductive potential of animals. It is shown that the reproductive success of males depends on the density of the population. Under physiological stress, such as a "peak" of the population size, the animals, against a background of accelerated aging, have activation of the hypothalamic-pituitary-adrenal axis, which contributes to oppression of the spermatogenesis process. The absolute weight of the testes is not always the determining factor in assessing the fertility of the animal. The informative indicators of the reproductive success of males and the population as a whole include the level of destructive changes in the endocrine and germinal regions of morphological defects of the testis and sperm.

[Combined effects of aluminium and immobilization stress on the reproductive system of male rats].

The evaluation of the isolated and combined effects of aluminum and immobilization stress on the reproductive system of male laboratory rats has been performed. We have established the influence of these factors on spermatogenesis and spermiogenesis: the development of degenerative processes in the testes, on specific hormonal status, apoptosis, increasing abnormal forms of epididymal sperms and reducing their mobility, and on the growth of early embryonic losses. Neither synergistic nor antagonistic effect in the combined aluminum and the stress action has been found.

[Reproduction of European bank vole (Myodes glareolus, Rodentia) under conditions of natural geochemical anomalies].

Estimates of abundance, morpho-functional state of ovaries, potential and actual fecundity of European bank vole, Myodes glareolus, inhabiting the territories of natural geochemical anomalies that are situated over ultra-basic rock and have an excess content of chrome, nickel, and cobaltare obtained. The population adaptive response to extreme geochemical conditions that facilitates the species survival under unfavorable environmental conditions and is manifested through an increase in potential and actual fecundity, decline of pre-implantation mortality, and decrease in proportion of females with pre-implantation losses is revealed. It is shown that in anomalous areas the intensity of folliculogenesis in mature voles is independent of the population cycle phase. As for immature animals residing within geochemical anomalies, an increase in size and numbers of follicles in ovaries is observed which is indicative of maturation fastening. An increase in potential and actual fecundity, as well as changes in morpho-functional state of ovaries, can be interpreted as means of birth rate accelerating which is supposed to compensate high postnatal mortality and maintain population abundance.

[Adaptation of the bank vole (Clethrionomys glareolus Schreber) to conditions of biogeochemical province with abnormally high content of nickel, cobalt and chromium].

Morphophysiological characteristics and peculiarities of adrenal gland of bank vole (Clethrionomys glareolus) were studied in the area of natural biogeochemical province with abnormally high content of nickel, cobalt and chromium. The control population inhabited area with usual content of these elements. We used 4-factor analysis of variance to estimate the influence of geochemical conditions, phase of population cycle, sex and reproductive state on the morphophysiological characteristics of animals and functional activity of adrenal gland. Animals from area with high concentration of Ni, Co and Cr show an increase in relative mass of adrenal glands, fascicular zone of adrenal cortex, size of cells and their nuclei. All these changes can be considered as an evidence of increased secretion of glucocorticoids. It is shown that phase of population cycle influences fatness of animals, size of nuclei, cells and adrenal cortex. Females in comparison with males are characterized with higher indexes of liver and adrenal gland, as well as morphometric indexes of adrenal cortex. The maturation of animals is accompanied with increase in body mass, fatness and relative mass of adrenal glands, the size of cortex zone, nuclei and cells themselves. It is supposed that the effect of "geochemical factor" results in intensification of glucocorticoid secretion of adrenal costex, thus increasing non-specific resistance of animals inhabiting area with high concentration of heavy metals. Such factors as "phase of population cycle", "sex" and "reproductive state", influence mineralocorticoid activity, glucocorticoid and androgenic functions of adrenal cortex. Some factors show synergetic effect.

[Evaluation of cytophysiological state of testis in forest voles living in the radioactively contaminated areas].

We made a cytophysiological analys of testis in Clethrionomus rutilus and Apodemus sylvaticus inhabiting a contaminated area of the East Ural Radioactive Trace (EURT). The study showed that in the norm these species differed in the total number of cells of spermatogenous epithelium, due to interspecific difference. In the sampling plot a concentration of 90Sr in Clethrionomus rutilus was 2 times higher than that in Apodemus sylvaticus. Maximum destructive changes in endocrine and exocrine (seminiferous tubules) section of testis and increased proliferation activity of spermatogenous epithelium were observed in Clethrionomus rutilus.Increased proliferation activity was found as a compensatory-protective reaction which promote the maintenance of the germ cell number. Such changes were not observed in Apodemus sylvaticus.

[Effects of ionizing radiation and xenobiotics on the spermatogenic epithelium of laboratory animals]. / Vliianie ioniziruiushchego izlucheniia i ksenobiotikov na spermatogennyi épitelii laboratornykh zhivotnykh.

Intact BALB/c and CBA mice differ in the overall cellularity of the spermatogenous epithelium, in the number of normal and pathological multinuclear cells. Exposure to small-dose radiation (0.25 and 1 Gy) causes profound changes in the spermatogenous epithelium in BALB/c mice. Then the increase in the abnormal forms of multinuclear and uninuclear cells leads to the disintegration and elimination of such cells, which affects the overall cellularity of the spermatogenous epithelium. A reduction in the proportion of multicellular cells, a compensatory-and-protective response that promotes the maintenance of the size of sex cells at the level optimal for fertilization. Upon small-dose exposure of rats to sixvalent chromium, there is a decrease in the whole population of germinitive cells and an increase in the multinuclear spermatocytes and spermatids. The rise in multinuclear cells is indicative of retarded cell maturation and differentiation at some stages of spermatogenesis, which reduces the number of spermatogenous cells.

[Histological analysis of the testis of Apodemus sylvaticus and Clethrionomys rutilus living in radioactively contaminated areas]. / Gistologicheskii analiz semennikov u lesnoi myshi (Apodemus sylvaticus) i krasnoi polevki (Clethrionomys rutilus), obitaiushchikh v usloviiakh povyshennogo radiatsionnogo fona.

We made a histological analysis of testis in Apodemus sylvaticus and Clethrionomys rutilus inhabiting a contaminated area of the East Ural Radioactive Trace (EURT). It showed that in the control these species different in the total number of cells of spermatogenic epithelium and in testis indices which were determined by interspecific differences. Concentration of 137Cs and 90Sr in Clethrionomys rutilus from the sampling plot was correspondingly 1.5 and 6.1 times higher than in the control, in Apodemus sylvaticus--1.9 and 3.6 times, correspondingly. Clethrionomys rutilus from the contaminated area had altered kinetics of spermatogenesis--an increased proliferation activity of spermatogenic epithelium. Maximum degeneration of cells was observed at the stage of spermatocytes. Such changes were not observed in Apodemus sylvaticus.

[The interaction of the thyroid-adrenal system with testicular function in mice subjected to gamma irradiation]. / Vzaimodeistvie tireoid-adrenalovoi sistemy s testikuliarnoi funktsiei u myshei, podvergnutykh gamma-oblucheniiu.

Single whole-body gamma-irradiation of BALB/c mice at a dose of 6.0 Gy results in an immediate response of the hypothalamus and hypophysis system: an increased generation of gonadotropin, adrenocorticotropin, and thyreotropin. The response of other organs manifests itself in an increase in testosterone, corticosterone and thyroxine in the organism. The above disturbances result in depression of the testicular activity and in fertility. The deficiency of testosterone is partly compensated by the enhancement of the adrenal secretion of adrogens.

[The role of the sex hormones in regulating the spermatogenesis process in different strains of mice irradiated at low doses of gamma quanta]. / Rol' polovykh gormonov v reguliatsii protsessa spermatogeneza u myshei raznykh linii, obluchennykh v malykh dozakh gamma-kvantami.

Intact BALB/c and CBA mice distinct in the total number of germ cells and testosterone level in blood plasma were exposed to doses of 0.1 and 0.25 Gy. Being tested 4-8 days after irradiation the BALB/c mice display compensatory-protective reaction which promote the maintenance of the germ cell number by active division of all spermatogonia types including the reserve ones. The CBA mice use the reserve later and only when the cells have reduced their proliferation activity or died. Testosterone plays a significant role in the process as the increase in its concentration stimulates proliferation activity and promotes mitosis block.

[The effect of low and sublethal doses of ionizing radiation on the function of the spermatogenic epithelium and the yield of dominant lethal mutations in different strains of mice]. / Vliianie malykh i subletal'nykh doz ioniziruiushchego izlucheniia na sostoianie spermatogennogo épiteliia i vykhod dominantnykh letal'nykh mutatsii u myshei raznykh linii.

There was a 30% increase in spermatozoids with microheads and a 3-fold increase in "young" spermatozoids at later times after irradiation of BALB/c mice a dose of 1.0 Gy. With radiation doses of 0.1-1.0 Gy, BALB/c and CBA mice (which differ in viability of spermatogenous cells, the number of Sertoli cells and total embryonal death rate) exhibited a significant increase in the preimplantation death at the stage of spermatogonia and stem cells. The results obtained indicate reduction of the fertilizing capacity of sperm which is probably realized as dominant lethal mutations.

[Role of gonadotropic hormones in the radiation response of the testis]. / Rol' gonadotropnykh gormonov v luchevoi reaktsii semennika.

In experiments on BALB male mice a study was made of the dynamics of changes in the level of gonadotropic hormones and testosterone during 1-32 days in conditions of gamma-irradiation with the dose of 0.155 C/kg and dose rate of 0.512 mA/kg. A correlation was found between the number of germ cells and the level of sex hormones in blood plasma of irradiated animals.