The posterior associative area (regio associative posterior - RAP) of the neocortex is included in the most complex functional systems of the brain and is involved in the implementation of inter-analyzer synthesis of information, perception, attention, memory and cognitive activity. To a large extent, the functions of RAP are determined by the microstructure of layer V, which provides a variety of connections within neural networks. Thanks to intravital methods of studying the human brain, ideas about the functional characteristics, but not about the structural transformations of various RAP zones in the process of postnatal development, are developing. The purpose of the study was age-related structural transformations of the internal pyramidal plate as part of zones of the posterior association area of the cerebral cortex that differ in structure, function and topography in children from birth to 12 years. The object of the study was the posterior associative area (fields 37 and 19) of the cortex of the left cerebral hemispheres of 73 boys aged from birth to 12 years who died from injuries without brain damage. On paraffin sections stained with cresyl violet according to Nissl, age-related changes in the thickness of layer V and the area of the profile fields of pyramidal neurons in its composition were studied at annual intervals. Image Tools technology (USA) was used to visualize the preparations, and the ImageExpert™ Gauge program (Russia) was used for morphometry. Mathematical data processing included ANOVA and Spearman's rank correlation analysis. Significant age-related changes in the microstructure of layer V RAP were observed during the first three years of children’s lives, as well as at the ages of 6 to 8 years. They occurred heterochronically, heterodynamically and differed in specific quantitative indicators in field 37 of the temporal region and field 19 of the occipital region of the cortex as part of the RAP. Local specificity of formative processes with their general uniform orientation was observed in subfields 37ac, 37a and 37d, in which microstructural parameters had varying degrees of interconnection during the development process, and also differed in terms, rates and intensity of observed changes.

Many modern chronic diseases lead to the development of cerebral hypoperfusion (brain ischemia). One of the top problems in the development of cerebral ischemia is the state of its non-neural structural components. The purpose of the study is the quantitative indicators of the structural components of the choroid plexuses of the rat brain at acute artificial ischemia. The object of the study were 30 white Wistar rats weighing 200-220 grams at the age of 4 months, divided into 6 equal groups of 5 animals: control group, experimental groups - after 1 hour, 1 day, 3 days, 7 days, 14 days of the experiment. Anesthetized animals were fixed, both common carotid arteries were prepared, which were then tightly ligated. The wound was treated with an antiseptic and sutured in layers. Then, after 1 hour, on days 1, 3, 7, 14, the rats were sequentially removed from the experiment. To assess the volume of the brain ventricles, sections were selected in which their cross-sectional area was maximum. The volume of the ventricles of the brain was determined on digitized micrographs at a 4-fold magnification by tracing their boundaries and subsequent calculations in the morphometric computer program ImageJ. Determination of volumetric fractions of the choroid plexuses was carried out by the stereological method on 50 serial sections using an ocular grid with 60 equidistant intersection nodes on a Micromed microscope at a magnification of 400 times. As a result of the study, it was established that during acute experimental cerebral ischemia, the choroid plexuses of the ventricles undergo significant structural changes at different time intervals, and the general and vascular architecture changes in all parts of the ventricles. In the lateral ventricles, the maximum area increases, the relative volume of the choroid plexuses decreases, the volume fraction of vessels inside the plexus increases, and the volume fraction of cells decreases. Other ventricles are characterized by specific dynamics. The results obtained contribute to the mechanisms of the pathogenesis of acute cerebral ischemia and its consequences.

The study of the morphological and functional features of the blood-tissue barrier of the skin, as an important component of the mechanism that ensures the homeostasis of general reactivity, is an actual task in histology and dermatology. The purpose of this study was to detection of the possible causes of damage to the blood-tissue barrier of human skin using a model studying mites of the kind Demodex. Author used material from skin scrapings and biopsies from 10 male volunteers aged 30-45 years. The material was examined for the detection of Demodex mites under a light microscope for a morphological study. For the study, a punch biopsy was used; after preparing the slides were stained with hematoxylin and eosin. Scanning electron microscopy was performed using a standard method. To determine the possible pathogenicity of the microflora, an analysis was carried out using a polymerase chain reaction with further cultivation and identification of the resulting material. The data obtained indicate the possibility of Demodex mites violating the integrity and normal structure of the components of the blood-tissue barrier of human skin. Obstruction of the hair canal and ducts of the sebaceous glands with skin detritus, destruction of sebocytes and the walls of the sebaceous glands with subsequent sclerosis, as well as leukocyte infiltration of the walls of the pilosebaceous complex were revealed. The durable chitins exoskeleton and structural features of the digestive tract of ticks protect them from the immediate reaction of local immune systems, and the complex mouthparts, hooks, and size of adult individuals contribute to the destruction of the structures of the human pilosebaceous complex. Over time, sclerosis of mechanically destroyed tissue areas and encapsulation of individuals occurs. Bacteria of the genus Bacillus, identified in mites, are one of the possible factors aggravating the negative effect of Demodex on human skin. The destructive effect of mites of the genus Demodex on the structures of the blood-tissue barrier of the skin, pathogenicity factors and structural features of mites can play an important role in their survival and spread in the pilosebaceous complexes of human skin, as well as in complicating the course of local inflammatory processes due to the destruction of the structures of the skin barrier.

The regeneration of skeletal muscle tissue after injuries of various origins is an urgent medical problem. In regenerating muscle, activation of hyperchromic myosatellite cells occurs, associated with the expression of myogenesis factors, including MyoD, proliferation and differentiation of nuclei. The effect of low-intensity green (520 nm) laser photobiomodulation on tissue has been little studied to date, but it can be assumed that laser radiation in the green region of the spectrum has a stimulating effect on the regeneration of skeletal muscle tissue. The purpose of the study was to analyze the effect of low-intensity photobiomodulation with a green laser (520 nm) on the density of MyoD+ nuclei in regenerating muscle. Three experimental groups of animals were formed: 0 – control (rats with an intact muscle); I – rats with an incised wound of m. gastrocnemius; II – rats with green laser exposure to the wound area, 60 s in continuous mode. A morphometric analysis of histological sections stained with hematoxylin-eosin and immune-histochemical methods was carried out. The results of the study showed that under the influence of green photobiomodulation there was an increase in the density of hyperchromic nuclei at periods of 1 and 3 days of the experiment. In the group exposed to the green laser, a significant increase in the distribution density of MyoD+ nuclei were found on the 3rd day of the experiment, both in the wound site and intact zones. At the same time, there was a significant increase in the distribution density of MyoD+ nuclei in the wound site compared to the intact zone on the 1st, 3rd and 14th days of the experiment, which indicates an active replenishment of the pool of nuclei of the destroyed skeletal muscle fibers. For the first time, it was shown that the effect of a green laser on skeletal muscles promotes early activation of myosatellite cells on the 3rd day compared to the 7th day during natural healing of a muscle wound. In addition, there is a wider coverage of muscle tissue by` the reparative process, since after green photobiomodulation the number of MyoD+ nuclei increase not only in the wound site, but also around it.

All over the world, work is actively underway to study the histogenesis and organogenesis of the pancreas, which makes it possible to answer a number of questions related to the mechanisms of this organ regeneration following damage of various origins. Spiny mice (Acomys) are a convenient laboratory model for studying prenatal development of internal organs because they have a relatively long intrauterine development period. These mice are predisposed to developing diabetes with obesity, hyperglycemia, glycosuria and ketonuria without insulin resistance under high-energy feeding conditions. The purpose of the study is the sequence of appearance and distribution of insulin-, glucagon- and somatostatin-positive cells to analyze the morphogenesis of the pancreatic islet apparatus during the prenatal development of spiny mice at different stages of gestation. The work was carried out on Spiny mice (Acomys). The 15th, 19th, 22nd, 24th, 28th, 34th, and 38th days of gestation were studied. The expression of glucagon, insulin and somatostatin in the developing pancreas was studied by immunohistochemistry methods. The first glucagon- and somatostatin-positive cells were found on the 19th day of prenatal development, and insulin-positive cells on the 22nd day. The first accumulations of endocrine cells appear on the 22nd day of gestation. The islets of Langerhans are clearly visible from the 34th day of prenatal development. In Spiny mice, during prenatal development in the pancreas, α- and δ-cells appear earlier than β-cells of the islets of Langerhans. The morphology of α-, β- and δ-cells and localization in pancreatic islets in humans and Acomys mice during prenatal development is similar. We believe that data on the development of the endocrine apparatus of the pancreas obtained in Spiny mice can be extrapolated to humans and the results of the work can clarify the processes of differentiation of endocrine cells of the islets of Langerhans in the human pancreas.

Hypothyroidism is one of the most frequently endocrine diseases caused by dysfunction of the thyroid gland. Hypothyroidism is accompanied by reactive changes in all organs and tissues, which is due to the presence of many targets for the thyroid hormones thyroxine and triiodothyronine and the role of these hormones in the animals and human's body. Striated cardiac muscle tissue is one of the most often involved in the reactive process during hypofunction of the thyroid gland in human, and the developing changes in the myocardium are of important clinical significance. The purpose of the study is ultrastructural changes in rabbit's cardiomyocytes with experimental hypothyroidism at the manifest stage of obvious signs. Male Soviet Chinchilla kind rabbits aged 12-14 months and weighing 3.1-3.5 kg (n=10) were used as the object of the study. The animals were divided into 2 equal groups: 1) experimental (n=5), in which experimental modeling of hypothyroidism was carried out through oral administration of the antithyroid drug thiamazole (10 mg/kg for 4 weeks), which inhibits the formation of thyroid glands hormones; 2) control (n=5), who received placebo and were in a physiological state. Electron microscopy was used to study ultrastructural changes in cardiomyocytes. According to the results of the study, numerous ultrastructural changes were revealed in all compartments of cardiomyocytes: in the nucleus (wrinkling, uneven contours of the nucleus and the appearance of invaginations of the nuclear membrane, chromatin condensation), in the contractile apparatus (thinning of myofibrils, the appearance of areas of excess contraction of myofibrils with contractures), in the energy apparatus ( change in the shape of mitochondria from oval to round, swelling of mitochondria, signs of destruction of the outer and inner membranes of mitochondria), in the sarcoplasmic system (expansion of the cisterns of the sarcoplasmic reticulum), in supporting apparatus (deformation of the intercalary discs between cardiomyocytes). These changes in the ultrastructure of cardiomyocytes probably underlie the impairment of myocardial contractile functions, apoptosis of cardiomyocytes and the gradual development of heart failure against the background of hypothyroidism.

There are a large number of studies devoted to the study of the branching of the internal iliac artery, the authors of which tried to classify the variants of its architectonics using various criteria. To understand the possible options for the architectonics of the internal iliac artery, it is essential to consider it from the point of view of the morphogenesis of the vascular network of the small pelvis. The purpose of the study is to study the branching options and morphometric characteristics of the internal iliac artery, its main branches, to identify the most common atypical, morphogenetically determined variants and to determine the frequency of their occurrence. The study is based on the use of a complex of intravital (vital) and postvital anatomical methods. Data from computed tomographic angiograms were processed in 100 patients, and X-ray angiograms of the pelvic arteries were processed in 50 patients. Preparations were performed on 20 anatomical objects, and 38 anatomical preparations using polymer embalming methods were also studied. As a result of the study, it was found that in most cases the internal iliac artery departed from the common iliac artery at the level of the L5-S1 intervertebral disc (76%). The typical level of division of the internal iliac artery into the anterior and posterior trunks was the intervertebral disc S1-S2 (68%), atypical - at the level of the L5-S1, S2-S3 vertebrae. This variant of the architectonics of the studied artery was observed in 65.8% of cases (n=378). Atypical variants of architectonics can be divided into 3 groups: first - variants of the origin of the internal pudendal and inferior gluteal arteries (19.7%); the second – from the obturator artery (3%); the third - from the iliopsoas artery (12%). The length and diameter of the main, anterior and posterior trunks of the internal iliac artery, respectively, were: 31.3±14 mm and 5.9±0.8 mm; 58.5±13 mm and 3.21±0.9 mm; 48.2±14 mm and 5.2±0.9 mm. Thus, the topography, architectonics and morphometric parameters of the internal iliac artery have a wide range of variability, which should be taken into account when performing complex surgical interventions on the pelvic organs.

The etiology of diseases of the knee joint is currently associated with dysplastic disorders that develop already in prenatal ontogenesis. The purpose of the study is to identify the features of differentiation of the histological structure, differences in points of fixation and direction of fibers of the patellar ligaments in the prenatal period of human development. The research materials included histological sections of the knee joints of 20 embryos and fetuses of both sexes aged from 6 to 38 weeks, stained with hematoxylin and eosin and Van Gieson. The study revealed the features of differentiation of cellular composition, the timing of the formation of collagen fibers of various types at different stages of prenatal ontogenesis and the two-layer structure of the medial and lateral suspensory ligaments, the patellar ligament, interconnected by solitary fibers. The stages of development of the anatomical structures of the ligamentous apparatus of the knee joint have been determined. The given structural features of the patellar ligaments allow us to assert the formation in the human fetus of a single morphological complex “quadriceps femoris tendon - patella”. The data obtained also suggest that the patella in the human fetus has a stronger fixation on the medial side than on the lateral side due to the tendon bundles of the vastus medialis muscle and the patellar ligament. By the time of birth, the patella and derivatives of the tendons of the quadriceps femoris muscle represent a single morphological complex of the knee joint. Between the superficial and deep layers of the patellar ligament there are solitary bundles of collagen fibers, passing from one layer to another, providing strength on the one hand, and synchronicity in the development of ligament functions on the other. This is precisely what can explain the deviation of the apex of the patella at the time of birth from the long axis of the femur to the medial side, causing the valgus position of the lower limb in newborns. The results of the study may have practical significance in improving the diagnosis and surgical treatment of developmental disorders of the musculoskeletal system in pediatric orthopedics and traumatology.

Variant anatomy of the lips of the mouth and the diversity of their morphometric characteristics, blood supply characteristics, sexual dimorphism, as well as individual, typological, ethnic and age characteristics play an important role in planning surgical and cosmetic interventions and procedures, providing a personalized approach when choosing treatment tactics. The purpose of this review is to analyze literature sources on morphometric indicators of the size and shape of the lips of a person’s mouth depending on gender, age and ethnicity. Materials and methods of research are information databases, scientific articles, reviews, monographs posted in the public domain and available in the collections of scientific medical libraries using the relevant keywords. As a result of the analysis, it was established that the diversity of ethnic features of facial parameters requires standardization of the typical lip shape characteristic of a certain group of people, taking into account other anatomical parameters. The final facial features of adult men and women develop after puberty. In men, the decrease in the relative height of the red border of the lower lip of the mouth is more pronounced, and the angle of protrusion of the lower lip is much greater. In addition to gender and ethnic variability, changes in the morphological features of the lips are one of the most significant characteristics of facial aging. Volume augmentation procedures are performed more often in younger patients, while contouring procedures are performed more often in older patients. However, plastic surgeons and cosmetologists do not have standards or ranges of “beauty parameters” that are typical for people with different face shapes. It was concluded that the variability of the topographic-anatomical relationships of blood vessels and nerves has not been studied for different types of structure and shape of the lips of the mouth, as well as the correlation of the morphometric parameters of the lips with the characteristics of other anatomical formations of the face. Research in this direction will be important not only in cosmetology, but also for identifying individuals during forensic medical examination.

Anniversary article dedicated to the 70th Anniversary of Doctor of Medical Sciences, Professor, Honored Scientist of the Russian Federation, Honored Worker of Higher School of the Russian Federation, Head of the Department of Normal Anatomy of the Kirov Military Medical Academy and Head of the Department of Morphology of the Saint-Petersburg State University Ivan Guyvoronsky.