Vol 162, No 2 (2024)

BACKGROUND: In fish embryogenesis, the yolk sac is the critical provisional organ, actively functioning during the embryonic and early postembryonic stages. Its primary role is trophic, facilitated in Teleostei by a specialized structure — the yolk syncytial layer (YSL). Ultrastructural transformations of this layer during gastrulation and early postembryonic development, as well as its interaction with migrating muscle fibers and melanophores, are probably necessary for the efficient use of nutrients by the developing embryo. The yolk sac’s role in the embryogenesis of Hemichromis bimaculatus may extend beyond current conceptions.

AIM: To study the structural organization of the Jewel Cichlid (H. bimaculatus) yolk sac during the embryonic and early postembryonic development.

MATERIALS AND METHODS: The research was involved 22 embryos and larvae of H. bimaculatus from 1 to 7 days after egg laying. The morphological features of the yolk sac were studied using light and transmission electron microscopy.

RESULTS: By day 2, the yolk sac was separated from the embryo by the trunk fold. Its main structure was the YSL, containing numerous nuclei, microvilli, mitochondria and phagolysosomes. The morphological features of the YSL were similar to those of the placental symplastotrophoblast and indicated high functional activity. The yolk sac mesenchyme contained blood vessels, migrating melanophores, and muscle fibers. The periderm, covered with a special shell, fuunctioned as the primary skin of the embryo. The transition to exogenous nutrition in Jewel Cichlid larvae was accompanied by a significant decrease in yolk sac size with its subsequent involution.

CONCLUSIONS: The trophic function of the yolk sac in H. bimaculatus is mediated by the YSL, which, during gastrulation and postembryonic development, interacts with a number of structures present in the yolk sac wall. Migrating muscle fibers promote activation of yolk granules; accumulation of toxic metabolic products is associated with melanophores. The special structure of the periderm protects both the yolk sac and the embryo from external influences.

BACKGROUND: Currently, researchers describe challenges in developing new treatments for fibrosis and cirrhosis: poor quality of preclinical models, insufficient trial duration, and lack of markers of therapeutic response. A separate task is to standardize the process of liver cirrhosis formation in preclinical trials, which is necessary to obtain accurate quantitative estimates in a short timeframe.

AIM: This study aimed to develop a mathematical model for the formation of liver cirrhosis during preclinical trials.

MATERIALS AND METHODS: Liver fibrosis and cirrhosis were induced in male Wistar rats using freshly prepared thioacetamide solution for 17 weeks. The area of connective tissue was determined as a percentage of the image area. The area of interlobular veins was measured in µm². The numbers of cells expressing the FAP marker and the α-SMA marker were counted. The level of mRNA expression of the Vegfa and Yap1 genes was assessed by real-time polymerase chain reaction. A mathematical model for classifying observations into stages was constructed using multiple logistic regression with stepwise selection of predictors, followed by calculation of sensitivity, specificity, and area under the curve with a 95% confidence interval based on ROC analysis.

RESULTS: As a result of the analysis, a mathematical model of liver cirrhosis formation was developed. The model is based on the values of two indicators: FAP⁺ cells and Yap1 mRNA and demonstrated good quality. The resulting value of the area under the ROC curve of 0.883 suggests good results for classifying cases.

CONCLUSIONS: The mathematical model makes it possible to differentiate the stage of liver cirrhosis from the stage of fibrosis during preclinical studies. It provides a foundation for studying the pathogenesis of liver fibrosis and cirrhosis, identifying new potential molecular targets for antifibrotic therapy, and reducing the number of expensive, labor-intensive laboratory tests.

BACKGROUND: Currently, there remains a high incidence of skin damage due to trauma, chronic diseases, burns, so it is important to study the issues of regeneration and treatment of skin wounds.

AIM: To conduct a morphological analysis of wound healing using aloe extract, hydrogel, and their combination in the experiment.

MATERIALS AND METHODS: The study involved 40 sexually mature guinea pigs, which were divided into a control group and 4 experimental groups (independent wound healing, application of aloe extract, hydrosorb gel, layer-by-layer application of drugs). Histological skin preparations were prepared on days 3, 7, 14, and 28 of the experiment. In each microslide, in 10 fields of view of the microscope at a magnification of ×50, morphometric parameters were measured in micrometers (µm): the thickness of the purulent-necrotic scab, inflammatory (leukocyte) infiltrate, granulation tissue, the length of the newly formed epithelium on days 3, 7, 14; the thickness of the epithelium, its length and the thickness of the connective tissue in the central part of the regenerate on the 28^th day. All data were subjected to statistical processing.

RESULTS: The medications led to a decrease in the inflammatory reaction, acceleration of the formation of granulation tissue, and partial wound epithelization by day 7 of the experiment; however, more pronounced signs of wound healing were observed with layer-by-layer application of aloe extract and hydrogel. By day 14, regardless of the application method, the use of medications demonstrated signs of enhanced wound healing. Thus, the length of the epithelium increased by 1.2–1.6 times, the depth of granulation tissue increased by 1.0–1.2 times compared to the control group. By the end of the experiment, all animals had complete closure of the wound with scar formation, while in the experimental groups showed signs of skin remodeling with appendages.

CONCLUSION: Morphological analysis showed that aloe extract, hydrosorb gel, and their combination accelerated the wound healing processes of full-thickness skin wounds in the experiment.

BACKGROUND: Endoscopic microsurgical techniques are used for sparing operations to remove foreign bodies of the pterygopalatine fossa, as well as neoplasms invading into it or growing out of it. These surgeries are performed not only in adults, but also in children as young as one month. For these surgeries, understanding the detailed structure and morphometric characteristics of the pterygopalatine fossa is crucial. However, detailed descriptions specific to children are lacking in the literature.

AIM: This study aimed to examine the size and shape of the pterygopalatine fossa and the relative location of nerve foramina in children aged 3 to 5 years (the period of primary dentition) using computed tomography data.

MATERIALS AND METHODS: To study the size and shape of pterygopalatine fossa, we analyzed anonymous archival frontal and axial computed tomograms of 12 children (24 pterygopalatine fossae) aged 3 to 5 years, obtained for examination of the underlying disease (brain pathology). All computed tomography scans were obtained using a helical computed tomograph (Somatom Sensation 64; Siemens, Germany) with an effective current of 63, 120 kV, a slice thickness of 0.5 mm, a reconstruction step of 0.7 mm, a collimation of 12×0.6 mm, Kernel U 70, a window width of 450 HU and a window center of 50 HU in University Clinic of Russian University of Medicine. The measurements were performed in the Cdviewer software after the preliminary measurements had determined sufficiently constant points on the contours of the pterygopalatine fossa of scans. On axial sections passing through the pterygoid canal, where the measurements had the greatest values, the following were studied: the largest width of the pterygoid canal (the distance between the anterior opening of the pterygoid canal and the orbital process of the palatine bone), the width of the medial wall and separately the width of the sphenopalatine foramen and the sphenoidal process of palate bone, the angle of deviation the medial wall from the sagittal plane, the width of the anterior wall (the distance between the most posteriorly protruding point of the anterior wall of the pterygopalatine fossa to the orbital process of the palatine bone), the greatest depth of the pterygopalatine fossa (posterior wall width) and the width of the pterygomaxillary fissure. The distance from the level of the orifice of the greater palatine canal to the anterior opening of the pterygoid canal and to the round foramen were measured on the frontal sections. According to axial tomograms, the spatial ratios between the orifice of the greater palatine canal and the round foramen and the anterior opening of the pterygoid canal, between these openings and the sphenopalatine foramen, between the round foramen and the anterior opening of the pterygoid canal were assessed.

RESULTS: The study found that the shape of the pterygopalatine fossa differs from the pyramid-like structure, featuring four distinct parts: the main one adjacent to the sphenopalatine foramen, and funnel-shaped constrictions at the vestibule of the pterygoid canal, greater palatine canal, and pterygomaxillary fissure. The data indicated minor individual differences in the size of the pterygopalatine fossa and the uniformity of its shape in children aged 3 to 5 years. The spatial relationships of the orifice of the greater palatine canal, the anterior opening of the pterygoid canal, the round foramen, and the sphenopalatine foramen openings determining the position of the nerves in the pterygopalatine fossa were clarified.

CONCLUSIONS: Pterygopalatine fossa in children aged 3 to 5 years (period of formed primary dentition) is characterized by a complex cavity structure, suggesting a different position of the pterygopalatine ganglion in it than is commonly believed. This circumstance, as well as for the first time the sizes of the pterygopalatine fossa determined by us, should be considered when developing surgical access to the pterygopalatine fossa and the pterygopalatine ganglion.

Restoring hyaline cartilage integrity remains a significant challenge in regenerative medicine. When damaged, the defect is replaced by fibrosis connective tissue, resulting in a loss of the biomechanical properties of the cartilage.

This review examines the intricate molecular mechanisms underlying reparative chondrogenesis and presents examples from a variety of animal species. It provides a comprehensive overview of the signaling pathways and cellular responses that promote cartilage repair, showcasing the regenerative abilities of fish and amphibians, including the little skate and axolotl, and surprising cases of chondrogenesis in mammals like the naked mole-rat and the Acomys mouse. Unraveling the dynamic interplay between growth factors, cytokines, and extracellular matrix components will shed light on the complex signaling pathways controlling reparative chondrogenesis.

The comparative analysis presented in this review reveals both conserved and species-specific molecular pathways involved in cartilage regeneration. This provides valuable information for translational studies. By uncovering the genetic and epigenetic determinants governing extreme examples of reparative chondrogenesis, this review provides a comprehensive framework for developing therapeutic strategies to improve cartilage repair in humans.

Ippolit Vasilyevich Davydovsky is an outstanding pathologist, academician of the USSR Academy of Medical Sciences, and professor who made a tremendous contribution to the foundations of modern pathological anatomy. Among his various scientific interests, he notably focused on the study of gerontology. This topic is quite relevant today since gerontology is beginning to become a separate medical specialty in medicine. The authors analyze the aspects disclosed in Davydovsky’s monograph “Gerontology,” as well as the ideas presented in other works on the issues described above. An overview of the main theories and provisions proposed by I.V. Davydovsky throughout his scientific career is presented. The importance of a comprehensive study of gerontology, which is inextricably linked with other branches of medicine, is emphasized. The natural philosophical understanding of the aging process is considered. The problem of atherosclerosis in geriatrics is described separately. Beyond his contributions to gerontology, the article highlights other foundational works by Davydovsky, including a textbook on general human pathology that underscores the inseparability of pathomorphology and pathophysiology as components of one discipline. His monograph on organopathology provides a comprehensive understanding of the pathogenesis of human diseases.

Thus, the scientist sought to dialogue with clinicians in his published works, thereby advancing the clinical-anatomical approach. The view of the community of pathologists on the scientific activity of I.V. Davydovsky, one of the most distinguished representatives of the field, is also interesting.