Vol 162, No 4 (2024)

BACKGROUND: The study of embryonic tissue and organ development from the perspective of comparative evolutionary histology enables the tracing of gradual changes in histogenetic processes and their continuity among vertebrate species. Data on the phylogenetic aspects of cloacal epithelium development remain fragmentary. Data on the histological structure of the epithelial lining of the anorectal canal (ARC) and cloacal subdivisions in embryogenesis across vertebrates (amphibians, birds, mammals) and humans are scarce in the scientific literature, with only a few published studies available. Research in this area is of particular relevance as it contributes to refining the theory of critical periods of embryogenesis and understanding the mechanisms of congenital malformations in humans.

AIM: To provide a comparative morphological characterization of the epithelial lining of the cloaca in cloacal vertebrates and the epithelial lining of the anorectal part of the digestive tract in rat and human embryos, based on the concept of heteromorphy.

METHODS: A single-center, observational, retrospective, uncontrolled study was conducted. The study material included the caudal region of the ARC in cloacal vertebrates (adult frogs, 13-day-old chicken embryos) and mammals (rat embryos at 9, 15, and 18 days of development). Additionally, histological specimens of human embryos (7–8 weeks of intrauterine development) were analyzed. Samples were fixed, dehydrated in alcohol, embedded in paraffin, and sectioned for Hematoxylin and Eosin staining, as well as Feulgen staining. Statistical analysis was performed, including calculations of the mean (M) and standard error of the mean (m).

RESULTS: The study revealed that different parts of the cloaca in vertebrates exhibit morphometric differences in their epithelial lining. The urinary part of the cloaca in vertebrates with a cloaca and chicken embryos is characterized by a heteromorphic structure. In mammalian embryogenesis (rat embryos), the formation of the cloacal membrane involves interacting histological systems derived from various embryonic primordia, including the peridermal epithelium, the allantoic epithelium adjacent to the periderm, and the gut-type epithelium of the hindgut. In human antenatal development, ARC formation is marked by the emergence of interaction zones between epithelial layers, which differ in structure and tinctorial properties.

CONCLUSION: Comparative analysis indicates that the embryogenesis of vertebrates, particularly in rats and humans, exhibits specific similarities in the composition of the epithelial lining of the ARC and the cloacal epithelium of amphibians and birds. The bilayered urothelium-like epithelium serves as a transient structure during embryonic development.

BACKGROUND: Striated cardiac muscle tissue in dysferlinopathy, a rare hereditary muscular dystrophy, has been the subject of limited research. Dysferlinopathy is traditionally considered a disease that predominantly affects skeletal muscles, as clinically significant heart failure is rare in affected individuals. However, myocardial involvement due to hereditary dysferlin deficiency has been described in only a few studies. The development of heart failure in these patients may result from both circulatory remodeling due to hypodynamia and direct myocardial damage. Structural changes observed in Bla/J mice with dysferlinopathy provide evidence for direct myocardial damage. However, submicroscopic alterations in cardiomyocytes and stromal myocardial cells (fibroblasts, endothelial cells, telocytes), as well as their role in the pathomorphogenesis of dysferlinopathy, remain insufficiently studied.

AIM: To characterize the ultrastructure of cardiomyocytes and stromal myocardial cells in the left ventricle of dysferlin-deficient Bla/J mice.

METHODS: Myocardial left ventricle fragments from Bla/J and C57BL/6 (control group) mice at 3, 6, 9, and 12 months of age were fixed and embedded in Araldite resin. Ultrathin sections (50–100 nm) were prepared, stained using Reynolds’ method, and examined via transmission electron microscopy.

RESULTS: Ultrastructural changes in the myocardium of Bla/J dysferlin-deficient mice included: destruction of the sarcolemma and intercalated discs; expansion and vacuolization of the sarcoplasmic reticulum; mitochondrial polymorphism. Additionally, myelin-like structures were detected in subsarcolemmal spaces and sarcoplasmic reticulum cisterns. In dysferlin-deficient mice, telocytes exhibited signs of degeneration. In contrast, the control group (C57BL/6 mice) showed no significant ultrastructural changes.

CONCLUSION: Ultrastructural evidence of myocardial damage in dysferlin-deficient Bla/J mice suggests a potential role of dysferlin in maintaining the structural integrity of cardiomyocytes and stromal cells.

BACKGROUND: Impaired reparative regeneration leads to insufficient extracellular matrix formation and the development of chronic wounds, necessitating a personalized therapeutic approach. In modern regenerative medicine, biopolymers such as silk proteins serve as the basis for wound dressings and drug delivery systems due to their unique properties. The biocompatibility, modulation of intracellular signaling pathways, and antibacterial activity of spidroin (spider silk protein), fibroin, and sericin (silkworm silk proteins) suggest their potential for wound healing applications.

AIM: To evaluate the effects of a spidroin, fibroin, and sericin-based cream on skin regeneration in rats.

METHODS: The study included 30 male rats, in which full-thickness excisional skin defects (20 mm in diameter) were created on the back. The animals were divided into three groups: the experimental group, which received daily applications of the test cream, and two control groups—one treated with 5% dexpanthenol and the other left to undergo natural wound healing. Planimetric and histomorphometric analyses, along with clinical blood tests, were performed to assess reparative regeneration and systemic reactive changes.

RESULTS: The application of the test cream significantly accelerated wound healing, with complete skin restoration in the experimental group by day 14 compared to the untreated control group. Analysis of inflammatory activity showed moderate granulocytosis and signs of acute posthemorrhagic anemia without pronounced inflammatory alterations in blood parameters. Additionally, immune cell infiltration was lower in the experimental group than in the controls.

CONCLUSION: The combination of spider silk proteins (spidroin) and silkworm silk proteins (fibroin and sericin) enhances cell migration, proliferation, and differentiation, promotes extracellular matrix formation, and exerts anti-inflammatory effects without immunogenic properties. These findings support the potential clinical use of this silk protein-based formulation as a therapeutic agent for treating wounds with pathological regeneration.

The development of technologies and methods for reprogramming cells at different stages of differentiation in vitro, ex vivo, and in vivo has become one of the most significant scientific and technological advances of recent decades. Each year, an increasing number of experimental studies report successful direct reprogramming of differentiated cells, including the generation of specialized neurons from glial cells in vivo. These technologies hold the potential to advance regenerative medicine to a fundamentally new level. However, despite the growing understanding of differentiation mechanisms and phenotypic plasticity, as well as expanding capabilities to guide these processes, the clinical application of cellular reprogramming remains a major challenge. This review discusses the definitions of cellular plasticity, recent advances in neuronal cellular reprogramming approaches using direct and indirect methods, and the key barriers to their clinical implementation.

Aneurysm is the most common pathology affecting the aorta. Advances in diagnostic and therapeutic approaches have reduced the associated mortality rate to 21.7%. Aneurysm formation involves morphological and functional remodeling of the aortic wall, leading to altered biomechanical properties of the vessel. Along the aorta, distinct functional zones with a high density of sensory receptors have been identified. These receptor zones have a specific anatomical distribution, with most sensory receptors localized in the tunica media of aorta. The vascular wall within these zones undergoes changes in lumen diameter that differ from those observed in other regions of the aorta. The morphological characteristics of these receptor-rich segments determine the unique biomechanical behavior of the vessel. The receptor zones of the aorta topographically correspond to the regions most frequently affected by aneurysm formation.

This year marks the 145^th anniversary of the birth of Boris Semyonovich Doynikov (1879–1948), an outstanding Russian physician and scientist renowned for his research in the histology and pathology of the central and peripheral nervous systems. His scientific works are regarded as classical contributions to the study of traumatic nerve alterations caused by chemical and mechanical injuries. The clinical and morphological analyses he conducted on the structure of somatic and autonomic nerves, as well as on their degeneration and regeneration following injury, remain among the most comprehensive in the global scientific literature and are of increasing practical relevance today.