Object of the study: Heart conducting system in fetuses and newborns, umbilical and maternal blood in cases of maternal essential hypertension, late gestosis and diabetes mellitus, protocols of autopsy of fetuses and newborns, case histories of deliveries, questionnaires for mothers of the sick children. Purpose of the study: To study pathogenic influence of arterial hypertension, diabetes mellitus, late gestosis in pregnant on the structure of main portions of heart conducting system of fetuses and newborns basing on the concept of intrauterine formation of precursors of disorders of HCS functioning in intrauterine onto-genesis. Methods of the study: Macroscopy, organometry, histology, histochemistry, immunohistochemistry, morphometry, electron microscopy, biochemistry, statistical evaluation. Practical significance: Histological histochemical, ultrastructural, morphometric peculiarities of HCS in fetuses and newborns were shown. Qualitative and quantitative differences in development of pathologicalprocesses in AH, LG, DM were determined. The complex clinical morphological approach to the study of HCS in fetuses and newborns allowed to work out and introduce into practice "Method of isolation of heart conducting system in fetuses and newborns" (№ 51984 А) with purposeful adequate isolation of main portions of HCS, which has practical significance not only for perinatal pathology but also at investigation of HCS in adults. Besides, the study of HCS MC in fetuses and newborns allowed to work out "Method of the study of HCS MC and myocardium" (№ 54701 А) and suggest it for application in scientific research of MC in the muscular organs and introduction to practical pathological anatomy. The obtained morphometry data of main portions of the HCS of fetuses and newborns will allow the morphologists to improve pathological diagnosis of cardiac pathology, especially in rhythm disturbances in fetuses during pregnancy as well as in newborns. The children born from mothers with AH, LG, DM should be included to therisk group and be regularly examined by cardiologists with preventive purpose because in the intrauterine period HCS was affected. Novelty of the obtained results: For the first time, HCS of fetuses and newborns was studied in mothers with AH, LG and DM with the use of a modern complex of morphology techniques (histology, histochemistry, immunomorphology, electron microscopy, polari-zation and phase microscopy, morphometry) aimed at the study of pathological and compensation adaptation processes in the HCS in the system "mother-fetus". For the first time, morphometric pa-rameters of HCS of fetuses and newborns at physiological preg-nancy and in presence of the studied pathology in the mother. It was established that the investigated pregnancy pathology, AH, LG, DM, effect specifically the vascular elements of fetal HCS. For the first time, it was shown that the result of affection of the vascular wall and disturbances of oxygeneration and nutrition of the parenchyma is the changes in the form of two degrees of sever-ity of myocytolytic and three degrees of contracture changes in sCMC with resultant death of some sCMC with hypertrophy of the rest and sclerosis of the stoma, which can be proved by revealing of interstitial collagen accumulation. It was noted that the peculiar-ity of microscopic picture of HCS in cases of maternal AH was di-agnosis of contracture disturbances of sCMC. Biochemical studies of the blood allowed showing that metabolic changes in the umbili-cal blood were similar to those in the maternal blood. Introduction: Main ideas and conclusions of the research were introduced into training process and research work of pathology departments of a number of medical universities of Ukraine as well as practical work of pathologists. Sphere of application: medicine, pathology.
