Morphology

Aging, or senescence (from Latin senex—old man), is a biological process characterized by the gradual degradation of organs and systems at various hierarchical levels of structural organization. Currently, the concept of cellular senescence is the prevailing framework for understanding organismal aging. It has been demonstrated that certain cells in developing (prenatal histogenesis) and definitive tissues undergo a series of morphofunctional changes, including increased cell size; disruption of the nuclear envelope; formation of distinct heterochromatin foci; acquisition of a secretory phenotype characterized by the production of proinflammatory cytokines, β-galactosidase, transforming growth factor β (TGFβ), and other factors; and mitotic arrest through the active transcription of p16INK4A and p21CIP1, genes involved in the induction of cellular senescence. It is hypothesized that such cells, referred to as senescent cells, represent an independent functional stage of cytogenesis within tissues rather than merely a transitional form between actively functioning cell lineage elements and those undergoing programmed cell death. The histogenetic significance of senescent cells in both physiological and reparative tissue regeneration, as well as their broader impact on histophysiology, remains to be fully elucidated. The pharmacologic elimination of senescent cells from tissues is an actively developing strategy in anti-aging therapy.

BACKGROUND: Constant illumination over a long period of time suppresses the hormone-synthesizing function of the pineal gland, leading to a decrease in melatonin levels and, consequently, to accelerated aging of the body, increased incidence of age-associated pathologies, including neoplasms, and shortened life expectancy. Melatonin has a pronounced antitumor effect. In particular, its antiproliferative effect is highlighted. Melanoma is one of the most malignant neoplasms in humans, originating from melanin-producing cells. In recent years, the proportion of older patients among patients with melanoma has been increasing, which makes it possible to classify this disease as age-associated. There is evidence that melatonin deficiency and the resulting disruption of the body’s circadian rhythms is one of the factors contributing to the development of melanoma.

AIM: To investigate the effect of exogenous melatonin on the morphological features of B16 melanoma in mice.

METHODS: The study was conducted on male hybrid mice of the BDF1 line (n = 60) at the age of 8 weeks, weighing 21–22 g. All animals received subcutaneous transplantation of B16/F10 melanoma in suspension. The mice were further divided into two groups, control and experimental. Animals of the experimental group were administered melatonin (Sigma, USA) at a dose of 5 mg/kg intragastrically from the first day of the study. On the 15th day after tumor transplantation, the tumor itself, as well as the lungs and liver, were removed. Pathomorphological examination of the tumor was performed, and the presence of lung and liver metastases was determined. Area of necrosis was measured on histological slides of the tumor stained with hematoxylin and eosin, and the nuclear-cytoplasmic ratio in tumor cells was calculated by measuring the cross-sectional area of nuclei and the cross-sectional area of cells. Graphing and statistical analysis of the results were performed using GraphPad Prism v8.41 (USA).

RESULTS: It was found that melatonin administration during the studied period reduced the mortality of mice with melanoma, decreased the incidence of tumor metastasis and tumor size. In addition, in melanomas of the experimental group of mice, signs of tumor regression in the form of foci of dystrophic and alterative changes were visualized, as well as a statistically significant increase in the area of tumor necrosis.

CONCLUSION: The present study showed that exogenous melatonin has a pronounced antitumor effect against B16 melanoma in mice. The obtained results allow planning more thorough and multidisciplinary studies for in-depth investigation of the mechanisms of melatonin antitumor effect.

BACKGROUND: The interaction between hemostasis and the immune system provides the body’s defense against external pathogens. However, the impact of blood coagulation on immune cell reactivity is poorly understood.

AIM: To investigate the effect of blood coagulation on its immunoreactive properties ex vivo.

METHODS: Donor blood samples were incubated with heparin (for plasma studies) or without heparin (for serum studies). Plasma and serum antioxidant activity was evaluated by chemiluminescence intensity after addition of hydrogen peroxide or ozonated physiological solution. Cytokine content was determined by enzyme-linked immunosorbent assay after incubation of blood with lipopolysaccharide (LPS) for 3 or 18 h.

RESULTS: Serum had a significantly greater antioxidant activity compared to plasma. The blood coagulation process markedly reduced both spontaneous and LPS-induced secretion of tumor necrosis factor TNF-α by blood cells, without significantly affecting the secretion of interleukins IL-1, IL-6, IL-8 and CRP. However, this process led to an increase in both spontaneous and LPS-induced secretion of vascular endothelial growth factor (VEGF) by blood cells. Serum samples with LPS also showed a marked increase in procalcitonin.

CONCLUSION: Blood coagulation enhances the antioxidant properties of blood, reduces the inflammatory activity of immunoreactive cells, thereby promoting regenerative processes.

BACKGROUND: Polyethylene glycol (PEG) is a water-soluble polymer that can be used as tissue embedding medium for obtaining histological sections. It has been previously reported, that PEG provides good preservation of tissue morphological characteristics comparable to that of epoxy resins, and the resulting slices can be used for immunohistochemical studies. Several methods of using PEG in histological studies have been described in literature, but they are disorganized and generally difficult to reproduce.

AIM: To evaluate tissue morphological characteristics and immunoreactivity in histological sections embedded in PEG.

METHODS: We investigated the possibility and results of transferring collectible (archived) samples of murine (Mus musculus) and weatherfish (Misgurnus fossilis) embryos through PEG 1000 and PEG 1500, as well as the peculiarities of sectioning, sample spreading, mounting on slides, and staining.

RESULTS: We compared the morphological characteristics of histological sections transferred through and embedded in PEG and paraffin wax. The advantages and disadvantages of using PEG for histological embedding were characterized. Immunohistochemical staining of sections using specific antibodies combined with chromogenic and fluorescent detection systems was performed.

CONCLUSION: It has been demonstrated that PEG provides preservation of structural features of cells and intercellular substance, also having a sparing effect on protein epitopes in tissues.

April 8, 2025, will mark the 120th anniversary of the birth of Gavriil Sergeyevich Strelin, a major scientist and educator. The authors have summarized the facts of the scientist’s biography and the main stages of his scientific and pedagogical activity. The main scientific work of G.S. Strelin was centered around the issues of radiobiology and the study of cell division regulation. G.S. Strelin worked for many years at the Central Research X-ray Radiological Institute in Leningrad. Gavriil Sergeevich was an honorary member of the All-Union Scientific Society of Rentgenologists and Radiologists and Deputy Chairman of the Problem Commission on Radiobiology of the USSR Academy of Medical Sciences. 15 theses were defended and about 200 scientific papers were published under his supervision. During the period from 1952 to 1960, G.S. Strelin headed the Department of Histology and Embryology of the First Leningrad Medical Institute, took an active part in the development of new methods of teaching histology as an academic discipline, attracted a number of new staff members to work at the department. The life and creative path of Gavriil Sergeyevich Strelin has served as an example for the younger generations of doctors, scientists and teachers for many years.