The purpose of the research: to submit a review of national and foreign literature on biological research of Hymenolepis nana. Materials and methods. Papers on morphology and biology of H. nana (starting from the first discovery of H. nana in 1851 by German parasitologist T. Bilharz until the present moment) written by 26 native and 11 foreign authors served as research material. When analyzing the literature, special attention was paid to the results of the morphological study and development cycle of H. nana taking into account the developmental stages of cestodes. Results and discussion. Specific data on morphology of H. nana and pictures of scolex and proglottids of the dwarf tapeworm using scanning electronic microscopy were provided. Structure of H. nana eggs was described in detail. Most papers are dedicated to the study of biological features of development. Sometimes, H. nana is reproduced by budding (passing through the following development cycle: megalospheres, metamers, invagination, scolexogenesis, larval cysts). Eggs were found in animals’ feces 17-18 days after infestation. H. nana lives in human body for several years, and sometimes 20-38 years. Issues related to the species identity of H. nana and H. fraternal, and mechanisms of transmission and prevalence of infection are discussed. Prevalence of hymenolepiasis in different countries depends not on climate conditions but on the degree of population density. Contamination of hands is an important factor influencing the frequency of hymenolepiasis autoinvasion in patients. The role of rodents as a source of H. nana infection is not essential.

No abstract

The paper analyzes the role of HOX genes in the processes of embryonic development of vertebrates. Based on the analysis, it is concluded that HOX genes are the most important regulators of embryonic development. The HOX genes predominantly realize their influence through specific HOX proteins that have the ability to regulate the expression of target genes. The order of expression of the HOX genes, as a rule, obeys the rule of temporal and spatial colinearity. This mechanism determines the temporal and spatial course of tissue morphogenesis during embryonic development and tissue regeneration in organisms that have reached the stage of maturity. The process of embryo morphogenesis, determined by highly conserved HOX genes, explains the appearance of the phylotypic period - the stage of embryonic development of vertebrates, at which embryos of different classes of vertebrates have distinct morphological similarities.

Introduction. Tobacco smoking can be designate as one of the most common world problems that negatively affects on the functional activity of the human body. The purpose of the study is to determine the degree of influence of tobacco smoking on the content of heavy metals (Zn, Cu, Pb, Cd) in biosubstrates of employees with different smoking experience in the absence of significant anthropogenic and man-made burden in the place of residence. Materials and methods. This study is experimental. To investigate the state of health of the population, hair samples were taken from 25 to 60 years male smokers aged, working at the Federal Penitentiary Service of Russia in the Ivanovo region, living in the same conditions. The study method included the use of inversion voltammetry to identify the relationship between smoking history and the level of accumulation of heavy metals in the human body. We used statistical analysis tools toward established the reliability of the results p<0.05. The data were compared with the established levels of the normal content of metals in the centile intervals of A.V. Skalny. Results. We determined that, depending on duration of smoking, the level of heavy metals (Zn, Pb, Cd) in the biosubstrates of the studied sample significantly increases (p<0.05). The indicators significantly exceed the physiological norm, while the copper concentration decreases, but is within the reference values. Limitations. The limitations of the study are limited to the possibilities of using the selected research methods and the presence of uncertainties in obtaining the characteristics of the objects of study. Conclusion. Tobacco smoking have influence on the content of heavy metals in the human body and accumulates during life.