Vol 162, No 3 (2024)

BACKGROUND: Intercellular gap junctions play a special role in the biology of cellular interactions. Their structural and dispositional changes can affect some biological functions, including disruption of electrical pulse propagation, which is primarily important for myocardial function.

AIM: The aim was to evaluate the morphological characteristics and localization of connexin 43-containing (Cx43⁺) gap — junctions and to determine their association with changes in myocardial morphology of the interventricular septum and clinical parameters in patients with hypertrophic cardiomyopathy.

MATERIALS AND METHODS: Morphometry and immunohistochemistry of interventricular septal myocardium were performed in patients with hypertrophic cardiomyopathy (n = 62, aged 18 to 61 years) compared with subjects without cardiovascular disease (n = 8, aged 25 to 54 years). Resection of the interventricular septum of the right ventricle was performed in patients with hypertrophic cardiomyopathy. Cx43⁺ gap junctions were identified in cardiomyocytes and their location and ultrastructural arrangement were determined. The data obtained were compared with clinical parameters of patients with hypertrophic cardiomyopathy.

RESULTS: In the interventricular septal myocardium of patients with hypertrophic cardiomyopathy, a redistribution of Cx43+ gap junctions from intercalated discs to the lateral surfaces of cardiomyocytes was observed. Gap junction changes are more frequent and more extensive in patients with hypertrophic cardiomyopathy than in the control group. They are typical of patients with the most severe morphological and functional cardiac condition, as evidenced by echocardiographic data such as significant thickening of the interventricular septum and a decrease in the volume of the left ventricular cavity. Morphologically complex remodeling of the myocardium is manifested by hypertrophy of the cardiomyocytes and partial loss of their myofibrils. Ultrastructurally, 28.1% of patients with hypertrophic cardiomyopathy had gap junction defects in the myocardium such as sites of localized divergence of intercalated disc membranes and abnormal ring structures formed by invaginations of gap junction-containing sarcolemma.

CONCLUSION: The location of Cx43⁺ gap junctions on the lateral surfaces of cardiomyocytes and changes in their ultrastructure suggest cardiomyocyte immaturity of the interventricular septum, which is typical of patients with hypertrophic cardiomyopathy and may cause a disruption of the electromechanical coupling of the myocardium.

BACKGROUND: Knowing the anatomical features of the inferior pyramidal space tendon of the fetal and neonatal heart (the tendon of Todaro, TT) is important for perinatal cardiac surgery (e.g., with access to the left atrium), but has been virtually unstudied.

AIM: The aim of the study was to evaluate the possibility of dissecting and evaluating the TT macromicroscopically and to obtain preliminary data on its presence, shape, size, branching and local topography in the fetal and neonatal heart.

MATERIALS AND METHODS: Fifteen samples of normal human hearts at 16–40 weeks of gestation were examined. Ten hearts were dissected under an Olympus SZX2-ZB10 microscope (Olympus, Japan) at a magnification ranging from 6.3 to 30×. The length and width of the TT were measured using a Levenhuk M1000 PLUS camera (Levenhuk, Russia) with a resolution of 10 Mpx and Levenhuk lite software. The arithmetic mean, standard deviation, median, extreme values, coefficient of variation and Spearman correlation coefficient (Rs) were calculated. Histologic sections were prepared from five hearts and stained using the Masson trichrome technique.

RESULTS: The TT was detected in all specimens and was always located in the intramyocardial space and/or in the loose connective tissue of the inferior pyramidal space. In all cases, the TT was originated from the right fibrous triangle, anterior to and above the atrioventricular bundle and node, where the TT was most monolithic. The TT then followed between the inferior border of the patent foramen ovale and the opening of the coronary sinus, ending at the valve of the inferior vena cava. In 6 out of 10 cases, the TT had no branches. In 4 out of 10 cases, it divided into two branches covering the opening of the coronary sinus. The TT fibers reaching the right coronary artery were dissected in one specimen. The median width of the TT at the inferior vena cava valve (0.35 mm) correlated with its length (4.63 mm; Rs = 0.821; p = 0.023) and width at the origin (0.24 mm; Rs = 0.929; p = 0.0003).

CONCLUSIONS: The inferior pyramidal space tendon of the heart in the late prenatal and perinatal period of human development is characterized by variable anatomy and constant topography. Variable structure is manifested by variations in tendon branching, a wide range of lengths and especially widths. Constant topography means that the tendon originates, runs, and ends in the same places. This tendon can be identified in fetal and neonatal hearts using macromicroscopic dissection.

BACKGROUND: It is well known that the thymus structure in the vertebrate phylogeny is characterized by a combination of conservative and highly plastic features. However, the question remains about the causes and patterns of evolutionary similarities and differences in human and animal thymus structure depending on level of organization, habitat, and adaptability.

AIM: The aim of the study was to identify the main patterns of change in the thymus microscopic structure in phylogeny by comparing the thymus structure in humans and various Chordata species.

MATERIALS AND METHODS: Light microscopy was used to determine the cortical/medullary and mitotic indices as well as the area of fibrous tissue, lymphoid tissue, and adipose tissue in thymus sections from 19 vertebrate species and humans. Thymocytes, thymic corpuscles, and the number and area of microcirculatory vessels were counted per conventional area unit. The study was conducted on immature animals of each species as well as on animals that had reached the second stage of maturity.

RESULTS: Comparative analysis shows that immature animals have predominantly similar thymus structures. Significant differences were observed in the parameters of age-related involution, which is characterized by significant magnitude and total fat degeneration in humans compared to animals. The morphological features of the thymus associated with thymocyte migration and maturation have the highest conservatism and include cortical/medullary and mitotic indices, the numerical density of thymocytes in the cortex, the total area of microcirculatory vessels, the relative area of lymphoid tissue. Human thymus, regardless of age, has a higher relative amount of fibrous tissue than vertebrates. In addition, some specific morphological features of the thymus corpuscles also vary.

CONCLUSIONS: The structural features of the human thymus were determined that changed in adaptation to specific conditions of the anthropogenic environment. The revealed morphological differences in human thymus are consistent with immunological hypothesis explaining the causes of age-related thymic involution. They correspond to the main points of Academician A.A. Zavarzin’s theory of parallel development of homologous tissues in vertebrate phylogeny.

BACKGROUND: Individual differences in hypoxia tolerance and hypoxia-inducible factor 1 alpha (HIF-1α) expression were identified in humans and laboratory animals. This was the basis for identifying groups of animals with low and high hypoxia tolerance. Animals with low hypoxia tolerance are known to have a more severe course of systemic inflammatory response (SIR). Sex differences in the severity of SIR in low hypoxia-tolerant animals have not been studied.

AIM: The aim was to evaluate sex differences in the severity of lipopolysaccharide (LPS)-induced SIR in Wistar rats with low hypoxia tolerance.

MATERIALS AND METHODS: Low hypoxia-tolerant animals were determined by their survival time in a hypobaric chamber under conditions equivalent to 11,500 m altitude (less than 60 s). The SIR was modeled by intraperitoneal administration of LPS at 1.5 mg/kg. Morphological changes in the lungs, liver, and thymus, as well as serum levels of endotoxin, corticosterone, HIF-1α, and TGF-β, were evaluated in males and females after 24 hours.

RESULTS: In control groups of low hypoxia tolerant rats, higher serum levels of HIF-1α, corticosterone and endotoxin were found in females compared to males. Compared to females, males usually have a higher thymic cortical volume fraction and lower subcapsular thickness. When LPS was administered to low hypoxia-tolerant females and males, sex differences in the severity of SIR were revealed. For example, in females, 24 hours after LPS administration, the neutrophil count in pulmonary interalveolar septa was higher, and random thymic involution with subcapsular zone narrowing developed without changing cortical volume fraction. Males demonstrated large abnormal lesions in the liver and more significant manifestations of accidental involution with a decrease in thymic cortical volume fraction. Serum corticosterone levels increased in females with SIR, and HIF-1α and endotoxin levels increased and TGF-β levels decreased in males.

CONCLUSION: LPS-induced SIR and immune responses in low hypoxia-tolerant Wistar rats depend on sex.

There are several professional societies around the world that are dedicated to finding and systematizing new information about programmed cell death. In 2018, the International Nomenclature Committee on Cell Death (NCCD) published the latest revision of the cell death nomenclature. Since then, the 2023 update of the consensus document on apoptosis has been published. The International Society of Cell Death (ICDS) has identified new trends in studying this important step in cytogenesis and histogenesis. The aim of this report is to present new information on the nomenclature of programmed cell death types, their classification, and the scientific and practical significance of the new findings to a national audience of experts.

The article is a tribute to Zakhar Katsnelson, who was a brilliant histologist, a great teacher, and a man of extraordinary integrity and morality. Zakhar Katsnelson became famous as one of the founders of broad comparative descriptive and experimental research of embryonal histogenesis. The authors of this article were interested in his personality, first of all, because he was their compatriot, born in the small Ural town of Irbit. The article provides biographical information about Katsnelson’s scientific career and outlines his professional activities. The most important of Katsnelson’s theoretical and practical scientific researches are described, such as the analysis of effects of chemical factors on the embryonic and larval development of amphibians, the study of the embryonic development of the suprarenal glands in farm artiodactyls, including the demonstration of the inadequacy of the capsule blastema theory and the proof of cell dimorphism in the suprarenal medulla, etc. Katsnelson’s role in cytological research in the USSR is highlighted. Special attention is paid to his participation in the campaign against the pseudoscientific concept of O.B. Lepeshinskaya, which contradicts the cell theory of R. Virchow. The article describes professor Katsnelson’s pedagogical and methodological activities and his talent as a teacher. The article reviews his works on teaching methodology and the history of morphology, which still play an important role in educating veterinary and medical students.