Vol 164, No 1 (2026)

This article honors Professor Vladimir I. Nozdrin (1947–2024) and his significant contribution to Russian histology. Nozdrin was born on January 27, 1947, in the village of Olovyannikovo (now the village of Kalinino, Stanovo-Kolodez Rural Settlement) of the Oryol District, Oryol Region. After graduating from the Oryol Medical College (1965), he entered the I.M. Sechenov First Moscow Medical Institute, from which he graduated in 1971. Following graduation, Nozdrin worked at various universities and research institutes in Moscow. Later, he founded the Department of Histology, Cytology, and Embryology at the Medical Institute of Oryol University, serving as its head from 1999 to 2020. Under his supervision, the department became one of the leading histology departments. From 1991 to 2016, Nozdrin also headed the pharmaceutical enterprise Retinoids JSC, which repeatedly received the Leader of the Russian Economy award. His primary research area was skin histophysiology. He investigated embryonic and postnatal morphogenesis of skin structures and their derivatives, establishing the patterns of their age-related transformations. Nozdrin investigated adaptive and reactive transformations of skin structures induced by various pharmaceuticals, as well as the biological properties of retinoids, their role in the body, and their potential for optimizing reparative histogenesis in the skin. Nozdrin devoted considerable attention to teaching histology. Together with co-authors, he prepared a series of textbooks and manuals on histology, cytology, and embryology, which were highly praised by both students and faculty. Nozdrin successfully worked on preserving the historical memory of prominent Russian and Soviet histologists, such as Babukhin, Eliseev, and Afanasyev. Of particular note is his work in organizing scientific conferences, including the Babukhin Readings in Oryol (10 conferences between 2002 and 2017), the 8th Congress of the International Association of Morphologists (2006), and several others. These events brought together leading morphologists from Russia and the CIS, as well as young researchers for whom such prestigious conferences became an invaluable professional experience. Professor Nozdrin made a significant contribution to the progress of cell biology, tissue biology, and embryology.

Considering their significant histophysiological effects, stem cells and extracellular vesicles are a promising approach in both military and civilian medicine for the treatment of acute radiation syndrome. This review aimed to summarize experimental data on the potential use of stem cells and their extracellular vesicles in radiation injuries. A systematic review was conducted to evaluate the efficacy of transplanting various types of cells (mesenchymal, hematopoietic, and neural stem cells, as well as progenitor cells) and extracellular vesicles in experimental radiation injury. The analysis included 13 Russian-language and 96 international publications from January 2002 to April 2024.

The review discusses the cellular effects observed in experimental models of radiation injuries and local radiation exposure at doses ranging from 1 Gy to 110 Gy. It summarizes the therapeutic effects of stem cells and extracellular vesicles, particularly their influence on stem cell niches. The primary mechanism behind this therapy is a paracrine effect mediated by extracellular vesicles. This paracrine action enhances the survival of endogenous stem cells while reducing their apoptosis. This cell therapy has been shown to increase survival of animals with bone marrow and intestine radiation injuries and accelerate recovery from local radiation injuries.

In recent decades, mesenchymal stromal cell transplantation has been the primary focus of research owing to its efficacy in hematological, intestinal, and cerebral acute radiation syndromes. Its therapeutic action is mediated through the suppression of inflammation and modulation of the microenvironment of endogenous stem cells, thereby improving their survival and reducing apoptosis.

BACKGROUND: The emergence of the coronavirus (SARS-CoV-2) caused a pandemic that led to an increase in morbidity and mortality among infected individuals. The SARS-CoV-2 variants circulating during that period, including Delta, were characterized by a broad spectrum of pathological effects at both the tissue and cellular levels. In 2025, the Omicron variant predominates, producing milder forms of respiratory conditions.

Among the key research questions related to SARS-CoV-2, considerable attention has been devoted to its pathogenicity, which is characterized by high virulence and the ability to induce systemic pathological processes.

Transmission electron microscopy is used to visualize virus–cell receptor interactions and to study the destructive impact of the pathogen on host cells. The findings of such studies form the basis for understanding the course and pathogenesis of the disease and contribute to vaccine development.

AIM: The work aimed to investigate SARS-CoV-2 virion reproduction and the trends of cytopathic effects in Vero E6 cell culture infected with Delta and Omicron variants.

METHODS: Ultrastructural analysis was performed on Vero E6 cell cultures infected with the Delta and Omicron SARS-CoV-2 variants. Infected cell cultures were fixed at three time points: 6, 18, and 24 hours after viral inoculation.

RESULTS: Most samples in both groups (Delta and Omicron) retained near-normal morphology 6 hours post-inoculation and exhibited numerous transport vesicles. At 18 hours, Delta and Omicron groups showed similar morphological changes, including vacuolization of the endoplasmic reticulum and Golgi complex. The Omicron group demonstrated altered mitochondrial morphology. Marked destructive changes were observed 24 hours post-inoculation. Both groups displayed cytoplasmic condensation, extensive organelle vacuolization, and numerous vesicles containing viral particles. Analysis of virion reproduction trends revealed an increase in viral particle numbers at 18 hours, followed by a decline in viral virion replication by 24 hours.

CONCLUSION: The study suggests similar mechanisms of cytopathic pattern formation in Vero E6 cells infected with the Delta and Omicron SARS-CoV-2 variants, along with active virion reproduction in cell culture between 6 and 18 hours post-infection.

BACKGROUND: There are currently no published studies on the role of mast cells in the pathogenesis of sporadic medullary thyroid carcinoma. However, their involvement in the progression of a variety of epithelial malignant neoplasms has been demonstrated. Furthermore, mast cell count may be an independent predictor of long-term progression-free survival in patients with pancreatic neuroendocrine tumors.

AIM: The work aimed to evaluate the potential of immunohistochemical detection of mast cells in the tumor microenvironment in sporadic medullary thyroid carcinoma.

METHODS: Histological specimens of sporadic medullary thyroid carcinoma were assessed using immunohistochemical detection of tryptase in mast cells. A convolutional neural network (CNN) model was then trained to segment positively stained cells, followed by quantitative analysis of the results.

RESULTS: Several potentially clinically significant parameters were identified, including correlations between mast cell count in the thyroid stroma and age; correlations between intratumoral mast cell count and T stage according to the TNM (8th edition) classification; and patterns of mast cell colocalization with other cells of the tumor microenvironment.

CONCLUSION: The study confirmed the presence of mast cells in the stroma of medullary thyroid carcinoma and revealed quantitative differences depending on tumor size. The observed active interactions of mast cells with atypical cells of sporadic medullary thyroid carcinoma and other components of the tumor microenvironment are a significant criterion for interpreting the biological effects of mast cells in this tumor type. These findings warrant further analysis to develop diagnostic algorithms and improve prognostic accuracy.

Major pathological processes, primarily inflammatory ones, are associated with disruption of the barrier function of the gastrointestinal mucosa. The structures of the nervous system that interact with cells of innate and adaptive immunity and modulate intestinal function remain insufficiently studied.

This work aimed to examine the human colonic mucosa in chronic slow-transit constipation (CSTC) using five clinical cases and to characterize the relationships between the mucosa, neural, and glial structures.

Immunohistochemical examination was performed on fragments of the descending colon mucosa obtained during surgical treatment of patients with severe CSTC. To identify inflammatory and immune cells, toluidine blue staining was used along with antibodies to CD68 and Iba-1 (ionized calcium-binding adaptor molecule 1) — macrophage markers; tryptase — a mast cell marker; PGP 9.5 (protein gene product 9.5), synaptophysin, and tyrosine hydroxylase — to detect neural structures; S100β protein — a glial marker; and serotonin and chromogranin A — markers of enterochromaffin cells.

In all examined cases of CSTC, hypertrophy of the lamina propria and leukocytic infiltrates were detected in the colonic mucosa, consisting mainly of blast forms of lymphocytic and monocyte–macrophage lineages (Iba-1⁺ and CD68⁺ cells), as well as mast cells. It was established that the innervation of the mucosal tissues involves postganglionic cholinergic fibers originating from neurons of the submucosal plexus microganglia. They are forming en passant terminal synaptic networks composed of varicose axonal bundles and accompanying neurolemmocytes. Close intercellular interactions were observed between parasympathetic nerve endings and glial elements, as well as immune–inflammatory cells. There was no sympathetic innervation of the mucosal tissues.

The presence of leukocytic infiltrates in the colonic mucosa of patients with CSTC, its intense innervation, and the accumulation of enterochromaffin cells in the epithelium indicate neurogenic inflammation. The inflammation affects the permeability of the enteral epithelium and modulates immune responses aimed at maintaining tissue homeostasis and restoring the barrier function of the intestinal wall mucosa in CSTC.

Mikhail R. Sapin, Academician of the Russian Academy of Medical Sciences, headed the Laboratory of Functional Anatomy at the Research Institute of Human Morphology of the Russian Academy of Medical Sciences for more than 40 years (currently the Research Institute of Human Morphology, a branch of the Petrovsky National Research Center of Surgery). Mikhail R. Sapin was not only the laboratory’s head of research, but he was also actively involved in the Institute’s life. As a member of the Academic Council, he helped define research directions and steer the Institute through difficult times. For many decades, Sapin served as a member of the Scientific and Methodological Council under the USSR Ministry of Health (later the Ministry of Health of the Russian Federation), and as Chair of the Functional Anatomy Task Group of the Morphology Research Council at the Presidium of the USSR Academy of Medical Sciences (later the Russian Academy of Medical Sciences). Sapin was well respected among morphologists; specialists from across the Soviet Union, and later from Russia and neighboring countries, sought his advice and guidance. For the morphological community, he was a true leader. Since 1974, he had served as Deputy Chair of the All-Union Scientific Society of Anatomists, Histologists, and Embryologists, becoming its Chair in 1988. In 1992, Sapin founded the International Association of Morphologists of the CIS Countries and served as its President; from 2006 to 2015, he was Honorary President of the Association.

In December 2025, the distinguished Russian histologist and educator, Doctor of Sciences in Biology, Professor of the Department of Histology, Cytology and Embryology of Orenburg State Medical University, and Honored Worker of Higher Education of the Russian Federation, Nikolai N. Shevlyuk, celebrated his 75th birthday. He was born on December 10, 1950, in the village of Linovitsk, Martuk District, Aktobe Region, Kazakh SSR, into a family of workers at the Shevchenko Machine and Tractor Station. In 1972, after graduating with honors from the Orenburg Pedagogical Institute (Faculty of Natural Geography, Department of Biology and Chemistry), Shevlyuk entered postgraduate studies at the Department of Histology, Cytology, and Embryology of the Orenburg Medical Institute. Upon completing his postgraduate training in 1975, he remained at the department, where he advanced from Assistant to Professor: 1975–1990 — Assistant; 1990–1998 — Associate Professor; since 1998 — Professor. Alongside his main position, from 1998 to 2006, Professor Shevlyuk worked at the Laboratory of Functional Cell Morphology of the Institute of Cellular and Intracellular Symbiosis, Ural Branch of the Russian Academy of Sciences, first as Senior, and later as Leading Researcher. From 2000 to 2017, he concurrently served as Professor at the Department of Zoology and Ecology of Orenburg State Pedagogical University. Shevlyuk was awarded the Candidate of Sciences in Biology degree in 1978 and the Doctor of Sciences in Biology degree in 1998; the academic title of Associate Professor in 1991 and that of Professor in 2000. Professor Shevlyuk is one of the leading scholars in the fields of ecological-morphological, comparative, and evolutionary histology, morphogenesis and regeneration, the history of science, and the methodology of teaching histology. The analysis of the vast body of factual material he has accumulated is reflected in an impressive number of scientific publications. Professor Shevlyuk was the first to describe the ultrastructure of Leydig cells in the testes of several vertebrate species and to identify key directions of adaptive transformations in testicular endocrinocytes under various destabilizing influences. Nikolai N. Shevlyuk founded the major Orenburg school of histology, whose cornerstone is the study of ecological morphology of the reproductive organs of vertebrates inhabiting anthropogenically transformed and natural ecosystems of the steppe zone of the Southern Urals. He has served as the head of this school for about 25 years. Colleagues, students, and the editorial board of the Morphology journal sincerely wish Professor Nikolai N. Shevlyuk good health, family happiness, unfailing optimism, and new scientific and creative achievements.