Vol 163, No 2 (2025)

The aim of this article is to analyze the contribution of Alexander Nikolaevich Bazhanov, a prominent Soviet histologist and representative of the Orenburg scientific histological school, to the development of fundamental problems in tissue biology and evolutionary morphology. Bazhanov was engaged in scientific research during the 1960s to 1990s. Bazhanov’s primary scientific research was devoted to the problems of embryonic histogenesis of the esophageal epithelium, the morphofunctional characteristics of esophageal mucosal structures, the study of evolutionary tissue changes, and tissue cultivation. His comparative histological studies and work on tissue culture led to the hypothesis that the esophageal epithelium originates from the prechordal plate. The findings obtained by Bazhanov served as the basis for the assertion that the prechordal plate is of endodermal origin. The results of his work made a substantial contribution to the development of the evolutionary direction in histology and promoted the advancement of research on debated problems in tissue biology. Bazhanov’s scientific legacy includes nearly one hundred articles and three monographs, two of which were co-authored. The importance of his work for the advancement of modern tissue biology was widely recognized during his lifetime. These studies have remained relevant even several decades after they were completed.

The aging of the population in developed countries is a trend of major medical and social significance. In this regard, the study of the etiology and pathogenesis of neurodegenerative diseases, as well as the search for effective treatment methods, is of particular relevance. For a long time, it was believed that metabolic waste products were drained from the brain parenchyma’s interstitial fluid into the ventricular system. However, the discovery of the brain’s glymphatic system has significantly advanced our understanding of the mechanisms underlying pathologies associated with impaired clearance of metabolites from the brain. This scientific review outlines the main directions in the study of the functional morphology of the glymphatic system under normal conditions. It provides a detailed description of two theories of cerebrospinal fluid outflow and presents a critical analysis of both Russian and international research data. Under normal conditions, the function of the glymphatic system is influenced by heart rate, intracranial pressure, pulse and arterial pressure, as well as the phase of the respiratory cycle. In addition, sleep quality, head position during sleep, and exposure to toxic substances directly affect glymphatic system activity. The review also highlights recent data on the glymphatic system of the visual organs. Further research into the morphofunctional characteristics of the glymphatic system under normal conditions may greatly expand our fundamental understanding of disease pathogenesis and contribute to the development of new approaches to treatment and prevention.

BACKGROUND: During embryonic development, the formation and differentiation of the mucosal tissues of the anal canal occur through the interaction of epithelia of different germ layer origins—ectodermal and enterodermal. The epithelial lining of the anorectal region of the rectum requires further characterization. Data on the histological structure and formation of tissue components in the anorectal canal during embryogenesis are relevant both theoretically (from an evolutionary perspective) and practically, as this region is a site of embryonic anomalies and neoplasms.

AIM: To describe the histogenetic features of anorectal lining formation in rats during embryogenesis.

METHODS: An observational, single-center, retrospective, uncontrolled study was conducted. The material consisted of the caudal portion of the anorectal canal of laboratory white rat (Rattus norvegicus) embryos at embryonic days 9, 13, 15, and 18. Morphological research methods were used. Histological analysis was performed on hematoxylin and eosin–stained sections.

RESULTS: On embryonic day 9, a cloacal membrane forms in the distal part of the embryo body. By day 13, the anorectal canal is formed and lined by cutaneous and intestinal epithelia, with a bilayered urothelium-like epithelium serving as a transitional interface. By day 15, this bilayered epithelium is replaced by clusters of rounded cells with hyperchromatic nuclei. On day 18, a clearly defined boundary is observed at the anorectal junction between the two genetically and morphologically distinct epithelia.

CONCLUSION: The findings indicate that, during embryogenesis in rats, a transient urothelium-like epithelium of the transitional zone exists between the cutaneous and intestinal segments of the anorectal canal, exhibiting distinct morphofunctional organization. In the later stages of embryogenesis, this transitional epithelium disappears, suggesting its provisional nature.

BACKGROUND: The insulin receptor-related receptor (IRR), a receptor tyrosine kinase, functions as a sensor of extracellular alkaline pH and is involved in renal bicarbonate excretion. High IRR expression has been detected in β-intercalated cells of the kidney, located in the distal tubules where bicarbonate secretion occurs. To create a new model for investigating sensitivity to pH changes, a unique INSRR knockout mouse line was developed on a C57BL/6 background.

AIM: To analyze morphological changes in kidney tissue in INSRR knockout mice compared with wild-type animals under normal conditions and during metabolic alkalosis.

METHODS: The study used littermate mice from a single generation, with genotypes confirmed by polymerase chain reaction. Two mouse lines were used in the experiment: INSRR knockout and wild-type. The animals were studied under two conditions—baseline and experimentally induced alkalosis. Morphometric analysis was performed on hematoxylin and eosin–stained kidney cryosections. The number of macrophages in kidney tissue was evaluated using immunohistochemical staining.

RESULTS: Morphometric analysis revealed that INSRR gene knockout did not lead to significant pathological alterations in kidney structure. However, significant differences were observed in parenchymal thickness, glomerular area, and collecting duct diameter in sections taken at the level of the renal pelvis. Differences were observed both when comparing the two mouse lines under normal conditions and during experimental alkalosis. Additionally, kidney size in knockout mice was smaller than in wild-type animals. Immunohistochemical analysis revealed no statistically significant differences in the number of CD206-positive (anti-inflammatory) macrophages in the kidneys under either normal conditions or experimental alkalosis.

CONCLUSION: Morphometric analysis of histological sections revealed increased parenchymal thickness in receptor tyrosine kinase knockout mice compared with wild-type animals under experimental alkalosis. Overall, knockout of the IRR receptor tyrosine kinase gene did not result in major pathological changes in kidney architecture. Thus, this genetically modified mouse line may serve as a model for physiological and molecular biological studies of metabolic alkalosis and its associated pathological processes.

On June 28, 2025, Professor Irina Alekseevna Odintsova—an esteemed histologist, talented educator, and outstanding individual—celebrates her 65th birthday. She is Head of the Department of Histology and Embryology at the S.M. Kirov Military Medical Academy, Doctor of Medical Sciences, Professor, and Honored Worker of Higher Education of the Russian Federation. This anniversary prompted us to briefly outline the key milestones of her biography and professional journey. Professor Odintsova’s life and work have been inextricably linked with the Military Medical Academy. For more than two decades, she has led the Department of Histology and Embryology, where her students and colleagues work productively and gain scientific experience under her guidance. Professor Odintsova is engaged not only in scientific research but also in extensive educational outreach. She initiated the tradition of organizing national histological conferences and academic meetings not only within the department but also at prominent venues across Saint Petersburg, transforming these events into noteworthy and anticipated gatherings for the entire Russian histological community. Her students, colleagues, and friends extend their warmest congratulations to Irina Alekseevna, wishing her good health, professional longevity, boundless energy, and happiness.