Postnatal Ontogenesis Research Articles

Skin morphology of five species of rock lizards of the genus Darevskia (Lacertidae, Squamata)

The microstructure of the tuberculate dorsal and lamellar ventral skin of the body in rock lizards of different ages (Darevskia raddei, D. nairensis, D. valentini, D. dahli, D. armeniaca) has been described for the first time. The thickness of the skin in the most xerophilic species (D. raddei) is less than that in the more hygrophilic species. Rock lizards have single or paired longitudinal skin folds that are not closed from the side, which stretch along the inner side of the scales to its distal edge. Small folds are also present in the lining of the squamous pocket; they consist of all layers of the skin and subcutaneous tissue. A large fold is able to completely block the cavity of the squamous pocket, the volume of which changes with the contraction of the subcutaneous muscle bundles reaching the bases of the scales. Small folds are also present on the scales of tuberous skin. In hygrophilic lizards (Zootoca vivipara), similar formations appear at later stages of postnatal ontogenesis than in rock lizards. The probable functional significance of the described skin structures is discussed.

Gonadotropin-releasing hormone and organs of the immune system

As a result of a literature search, the physiological aspects of the gonadotropin-releasing hormone (GnRH) influence on immune organs, such as red bone marrow, thymus, spleen and lymph nodes, were considered. The use of GnRH drugs leads to the replacement of red bone marrow with yellow one with an increase in the content of lymphoid and myeloid progenitor cells. In parallel, processes of osteoporosis occur due to increased bone resorption with corresponding changes in calcium metabolism and a decrease in the density of various bone tissues. At the same time, there are papers reporting no effect of GnRH on bone density and changes in calcium metabolism. GnRH acts on the thymus during embryonic development, and in postnatal ontogenesis, and during inflammation and age-related involution processes. Not only GnRH causes changes in the thymus; the thymus may also influence on the GnRH system. A direct effect of GnRH on spleen cells had not been detected, but the weight of the organ changed as a result of active immunization against GnRH in experiment. Unfortunately, very few articles demonstrate the physiological mechanisms of immunomodulation in such conditions. In any case, the obvious insufficiency and contradictory of publications on each aspect of GnRH effects indicates that they have been poorly studied, and it’s advisabile of further continuing not only applied research, but also fundamental investigations, due to its possible high prospects for creating immune control systems.

Peat smoke exposure as a risk factor for deterioration of postnatal development

Introduction. In connection with the growing number and scale of wildfires, the problem of the toxic effect of biomass combustion products is relevant both in Russia and abroad. Data on the consequences of wildfire smoke exposure at various stages of ontogenesis are extremely scarce. The presence in smoke substances that, in addition to general toxic effects, have reprotoxic, gonadotoxic, and genotoxic effects, determines the need to study its effect on the reproductive potential and health of offspring. The purpose of the study was to assess the postnatal development of the offspring, the parent generation of which was exposed to peat smoke during puberty. Materials and methods. Exposure to peat smoke was carried out once for four hours on the 35th day of life for female and on the 45th day for male rats. The average concentrations of carbon monoxide in the exposure chambers were 29.3±11.1 mg/m3, and ultrafine PM2.5 particles – 0.39±0.61 mg/m3. At puberty, peat smoke exposed rats were mated with intact partners. In rat pups from the offspring there was studied the trend in body weight gain, physical development, and sensory-motor reflexes were assessed. Results. Acute exposure to peat smoke during puberty in white rats adversely affects the development of their offspring. A significant lag in the physical and sensory-motor development of rat pups from the offspring of animals exposed to smoke was revealed in comparison with rat pups from the control group. Limitations. The study was limited to the study of postnatal development of offspring obtained from rats exposed to peat smoke during puberty. Conclusion. Exposure to peat smoke during puberty leads to a delay in the physical and somatosensory development of the offspring during early postnatal ontogenesis.

Regulation of vascular smooth muscle cell contraction during early postnatal ontogenesis

Growth of the body in early postnatal ontogenesis is associated with changes in the functioning of many organ systems, including the cardiovascular system. The circulatory system of newborns is characterized by numerous structural and functional features, which at the systemic level is manifested in a significantly lower level of blood pressure. This review describes the differences in the mechanisms of regulation of vascular smooth muscle cell contraction in early postnatal ontogenesis and in adulthood, including age-related changes in the functioning of ion channels, which activity affects membrane potential level and intracellular concentration of calcium ions, as well as changes in calcium sensitivity of the contractile apparatus. The final section of the review discusses the connection between the mechanisms regulating contraction and differentiation of vascular smooth muscle cells during maturation.

During Postnatal Ontogenesis, the Development of a Microvascular Bed in an Intestinal Villus Depends on Intussusceptive Angiogenesis.

The mechanisms responsible for the growth and development of vascular beds in intestinal villi during postnatal ontogenesis remain enigmatic. For instance, according to the current consensus, in the sprouting type of angiogenesis, there is no blood flow in the rising capillary sprout. However, it is known that biomechanical forces resulting from blood flow play a key role in these processes. Here, we present evidence for the existence of the intussusception type of angiogenesis during the postnatal development of micro-vessel patterns in the intestinal villi of rats. This process is based on the high-level flattening of blood capillaries on the flat surfaces of intestinal villi, contacts among the opposite apical plasma membrane of endothelial cells in the area of inter-endothelial contacts, or the formation of bridges composed of blood leucocytes or local microthrombi. We identified factors that, in our opinion, ensure the splitting of the capillary lumen and the formation of two parallel vessels. These phenomena are in agreement with previously described features of intussusception angiogenesis.

The Influence of Experimental Chronic Antenatal and Acute Postnatal Hypoxia on the Morphological State of the Liver Stromal Component

BACKGROUND: At present, the asymptomatic course of liver pathology in early childhood remains an urgent problem. AIMS: The objective of the study was the detection of morphological features of the stromal component of the liver of rats, which were at different stages of postnatal ontogenesis and were exposed to chronic antenatal and acute postnatal hypoxia (APH). MATERIALS AND METHODS: The study material was rat liver tissue of the control group, the APH group, and the chronic antenatal hypoxia (CAH) group. RESULTS: From day 1 to day 35, CAH leads to an increase and growth of the stromal component in the liver of offsprings due to the development of sclerotic changes caused by activation of collagen formation with a predominance of mature collagen Type I over immature collagen Type III on day 1 and day 14 of the experiment and predominance of collagen Type III over collagen Type I on day 35 of the experiment, increasing the expression of fibronectin. Starting from day 14, APH leads to the development of sclerotic changes in this organ which increase to day 35, less pronounced compared to the detected sclerotic changes in CAH, and manifest in increased expression of fibronectin, activation of collagen formation with a predominance of collagen Type I over collagen Type III on days 14 and 35 of the experiment. CONCLUSION: CAH from day 1 and APH from day 14 of postnatal life lead to the development of sclerotic changes in the liver of offsprings, which are more pronounced in cases of simulation of CAH and increase with age.

Perinatal hypoxia augments contractile impact of NADPH oxidase-derived ROS in early postnatal rat arteries.

Reactive oxygen species (ROS), including those produced by NADPH oxidase (NOX), play an important vasomotor role, especially at early postnatal period. Mechanisms for regulating vascular tone can change significantly due to neonatal asphyxia and accompanying hypoxia. We tested the hypothesis that normobaric hypoxia (8% O2) for 2 h at the second day of life changes the functional contribution of NOX-derived ROS to the regulation of agonist-induced contraction in early postnatal rats. We studied saphenous arteries from 11- to 14-day-old male offspring using isometric myography and Western blotting and assessed the content of biochemical parameters in blood serum. The values of main biochemical parameters in blood serum and the protein content of NOXs and superoxide dismutases in arterial tissue did not differ between "Control" and "Hypoxia" pups. The NOX inhibitor VAS2870 equally reduced the contractile responses of arteries to α1-adrenoceptor agonist methoxamine in "Control" and "Hypoxia" pups, but its effect was more pronounced in the arteries from "Hypoxia" pups when vasocontraction was evoked by the agonist of thromboxane A2 receptors U46619. Perinatal hypoxia at the second day of life increases procontractile influence of NOX-derived ROS to the regulation of U46619-induced vasocontraction in the systemic arteries at early postnatal ontogenesis. Nothing is known about programming effects of perinatal hypoxia, including birth asphyxia, on the ROS-mediated regulation of contraction in systemic arteries of early postnatal organism. 2-h normobaric hypoxia (8% O2) in rats at the second day of life increases the procontractile contribution of NOX-produced ROS to the regulation of U46619-induced vasocontraction in the systemic arteries at early postnatal ontogenesis. This fact may serve as a risk factor for the development of various disorders at later developmental stages and should be considered regarding the therapy for newborns who have suffered neonatal asphyxia.

The Structure Of The Rat Thymus During Late Postnatal Ontogenesis And Its Changes When Exposed To An Energy Drink

The Structure Of The Rat Thymus During Late Postnatal Ontogenesis And Its Changes When Exposed To An Energy Drink

Morphological and functional spleen development in crossbreed rabbits

The accelerated growth of muscle mass in productive broiler breeds is often associated with delayed organ development of integral body systems, particularly the immune structures. The spleen is the largest secondary immune organ in the mammalian body and is responsible for initiating immune responses to blood-borne antigens. It can only perform this function successfully if all of its tissue components are fully morphologically and functionally mature. The spleen was studied in meat production rabbits (early maturing crossbreed Hyplus) at 1, 10, 20, 30, 60 and 90 days of age. Morphological studies included anatomical dissection, clarification of topography, determination of mass parameters, preparation of smears and histological sections. Spleen histological sections were stained with haematoxylin and eosin, according to Van Gieson, and impregnated with silver nitrate, followed by microscopy. Qualitative and quantitative indicators of spleen cellular and tissue component development were determined using ImageJ software. It was found that in crossbred rabbits the topography of the spleen corresponds to general anatomical principles of localisation, has a fixed place and is an anatomically formed organ. In day-old animals, the histological differentiation of the spleen is limited to the connective tissue stroma and the parenchyma. The organ's parenchyma is formed by reticular tissue, with hematopoietic and lymphoid cells among the cells, without differentiation into white and red pulp. In 10-day-old rabbits, the white pulp is represented by the periarterial lymphatic sheath (PALS) and marginal zones. Single primary lymphoid nodules without germinal centres are seen in the spleen from 20 days of age. By 30 days of age, the white splenic pulp has all the major structural and functional zones, including formed lymphoid nodules with germinal centres and mantle zones. During the second and third months of life, the spleen gradually increases the relative area of all white pulp functional zones, reaching a maximum at 90 days of age. In productive rabbits, the cellular composition of the splenic white pulp is represented by lymphocytes (small, medium, large), reticular cells, macrophages and plasma cells. During postnatal ontogenesis, the number of small lymphocytes increases in all white pulp functional zones, reaching maximum values in 90-day-old animals. On the contrary, the relative number of medium and large lymphocytes decreases. The number of reticulocytes in the periarterial lymphatic sheath and lymphoid nodules zones does not change significantly, and in the marginal zone it decreases substantially by the end of the study. The results of determining the timing of morphological and functional maturation of immunocompetent structures in the spleen of meat rabbits are of great biomedical and economic importance. They will serve as a control for comparing changes in rabbit spleen lymphoid tissues during the development of pathological processes, as well as under the influence of external factors.

Neuropeptide Y is involved in the regulation of the frequency and strength of rat atrium spontaneous contraction

BACKGROUND: The relevance of the problem increases due to the established cardioprotective effect of neuropeptide Y in pathological conditions such as hypertension, heart failure, and its possible therapeutic use in cardiovascular diseases. AIM: Study of the effect of neuropeptide Y on the frequency of spontaneous activity and amplitude-time parameters of the myocardium contraction of the rats’ right atrium during different periods of postnatal ontogenesis. MATERIAL AND METHODS: The experiments used 73 white outbred rats of 7 days (n=23), 21 days (n=25) and 100 days (n=25) of age. Using the classical strain-gauge method, the parameters of isometric contraction of isolated rat atrial myocardium were determined with the addition of a non-selective Y-receptor agonist. The isometric contraction curve was processed using the Chart 8.0 program. Statistical processing of the results was performed in MS Excel and IBM SPSS Statistics 2020. The significance of the differences was calculated using the Student’s t test. Data were presented as mean ± error of mean (M±m); n was the number of atrial myocardium preparations used. Changes were considered statistically significant at p 0.05. RESULTS: Neuropeptide Y at a concentration of 10–7 M reduces the frequency of spontaneous activity of the right atrium strips of rats with a preserved sinus node in 7, 21 and 100-day-old animals by 8.1%, 15% (p=0.038) and 7.9% (p=0.046) respectively in comparison with the control value. The amplitude of isometric contraction of the atrial myocardium in 7-day-old animals decreases by 12.4% (p=0.041), the duration of contraction decreases in 21-day-old animals by 12% (p=0.040), and in 100-day-old animals does not change compared to control. CONCLUSION: Neuropeptide Y reduces the frequency of spontaneous activity, increases the contraction duration, reduces the isometric contraction amplitude of rat myocardial strips in early postnatal ontogenesis.

Nfluence of extracellular acidosis on the functional contribution of KATP and TASK-1 potassium channels to the regulation of vascular tone in early postnatal ontogenesis

The activity of many proteins and, as a result, of the mechanisms of vascular tone regulation depends on pH. A decrease of pH (uncompensated acidosis), usually causes relaxation of blood vessels, which has been studied in sufficient detail for an adult, matured organism. However, the effect of acidosis on the mechanisms of vascular tone regulation in the early postnatal period remains almost completely unexplored. The aim of this work was to study the effect of extracellular metabolic acidosis on the functional contribution of KATP and TASK-1 potassium channels to the regulation of vascular tone in early postnatal period. We modeled extracellular metabolic acidosis (pH 6.8, equimolar replacement of NaHCO3 with NaCl in solution) and studied isometric contractile responses of the saphenous artery in rats aged 3–4 months and rat pups aged 12–15 days. Arterial contraction to the α1-adrenergic agonist methoxamine at pH 6.8 was reduced compared to normal pH 7.4 in both 3–4-month-old and 12–15-day-old rats. The KATP channel blocker glibenclamide did not change the arterial responses to methoxamine, neither at pH 7.4 nor at pH 6.8 in any of the age groups. The TASK-1 channel blocker AVE1231 did not alter arterial contractile responses at any pH in 3–4-month-old rats. However, in 12–15-day-old rat pups, the increase in contractile responses to methoxamine under the influence of AVE1231 was less at pH 6.8 than at pH 7.4. Thus, the results of this work demonstrate that acidosis reduces the contractile activity of the arteries of 3–4-month-old animals and animals during early postnatal ontogenesis, while in the latter, the anticontractile role of TASK-1 channels decreases, and KATP channels do not affect the regulation of vascular tone, either under normal, or at acidic pH in any of the age groups.

S100ß are immunopositive glial cells of the rat heart in early postnatal ontogenesis

The study of the innervation of the main organ of the cardiovascular system, the heart, is an important problem of modern neurobiology. Most research on this topic is devoted to the study of nervous structures in humans and animals; glial cells are studied less. Nevertheless, glia plays an important role in maintaining the metabolism of the nervous apparatus and, by producing biologically active substances, affects the state of tissues and organs, both normally and in pathology. The purpose of this work is to study glial cells in the rat heart in the early postnatal period of development using an immunohistochemical marker, the S100β protein. The object of the study was the heart of Wistar rats at the age of seven days of postnatal development (P7) (n=12). Using immunohistochemical detection of a neural marker - the PGP 9.5 protein, the neural structures of the heart of P7 rats were studied. To identify glial cells, immunohistochemical detection of the S100β protein was used. The S100β protein belongs to the group of calcium-binding proteins and is expressed in glial cells of the central and peripheral nervous system. The study revealed a significant difference in the innervation of the upper and middle parts of the heart of P7 rats. Only in the right atrium was a pronounced concentration of nerve structures found, mainly in the region of the sinus node. It was established that in P7 rats, proepicardial cells express the S100β protein, characteristic of neurolemmocytes. A hypothesis has been put forward about the pos sibility of developing part of the glial cells of the myocardium of the right atrium and right ventricle from progenitor multipotent cells of the proepicardium through epithelialmesenchymal transformation.

The Effect of Hypokinesia on the Dynamics of the Formed Elements of Blood during the Embryonic Period of Prenatal Development in Pregnant Rabbits

The erythroformula and leucoformula indicators changed in the rabbits that experienced hypokinesia during the embryonic stage of pregnancy. Compared to the rabbits that spent the pregnancy period under normal conditions, changes in concentrations of leukoformula indicators such as leukocytes, lymphocytes, monocytes, and granulocytes were detected in rabbits exposed to hypokinesia. While significant changes in erythroformula indicators: erythrocytes, average corpuscular volume of erythrocytes and hemoglobin capacity, erythrocyte sedimentation rate did not occur. The results of our studies have shown that prenatal hypokinesia causes noticeable changes in the blood coagulation system. On the other hand, changes in the coagulation system under the influence of prenatal hypokinesia were found to occur in the first periods of postnatal ontogenesis, had a continuous nature, and were maintained until the full maturity of postnatal development. Due to the effect of the hypokinesia factor, the changes in the mentioned indicators lead to the emergence of severe pathological diseases in most cases.

Механизмы поражения соединительной ткани при фибромускулярной дисплазии и атеросклерозе: возможности визуализации

Multifocality, high prevalence and lack of consensus on the etiopathogenesis of atherosclerosis and fibromuscular dysplasia (FMD) in the human population are well known. However, the issues of comorbidity and mechanisms of connective tissue damage in these pathologies remain unclear. The purpose of this study was to determine the leading causes of pathological arterial stenosis in patients with clinical signs of vascular disorders. Materials and methods. The research involved 67 patients (mean age 51.12 ± 13.12 years) with clinical signs of vascular disorders, who had received neurological or neurosurgical treatment at Surgut Clinical Trauma Hospital. The subjects underwent computed tomography angiography of brachiocephalic and intracranial vessels. To assess the internal stigmatization of the processes under study, author’s scales were developed. Results. The data of the author’s scales clearly indicate the influence of the genetically determined FMD process on the manifestations of atherosclerosis. The most frequent combinations of FMD stigmas and atherosclerotic lesions identified in the course of the study can serve as markers of the severity of these pathologies. The results allow us to view FMD and atherosclerosis in the context of morphofunctional connective tissue disorders. Paradoxically, despite the systemic nature of the two processes, their gross manifestations were clearly localized. This is probably due to the time interval of connective tissue cell damage and its nature. In our opinion, pathology in atherosclerosis develops during postnatal ontogenesis due to the increasing cytokinetic activity of connective tissue cells under the influence of various factors (atherogenic lipoproteins circulating in the vascular bed, microbiome disturbance, etc.). In FMD, fibroblasts get damaged by genetic mutations at the stage of embryonic development (vasculogenesis), gross stigmas are formed in areas of blood vessels with the most rapid growth due to the haemodynamic conditions of the onset of blood circulation (angiogenesis).

Рост и развитие бычков лимузинской породы различных генотипов в постнатальном онтогенезе

The purpose of research is to study the growth and development of Limousin bulls of various genotypes in postnatal ontogenesis. Objectives: to study of weight growth, absolute, average daily gains in live weight and relative growth rate of young animals by age periods and for the entire period of growing and fattening; to study of the linear growth of bulls in postnatal ontogenesis based on the dynamics of body measurements and body composition indices. The objects of the study are bulls of the Limousin breed of various genotypes obtained from the mating of cows of French, Australian and local selection with bulls of local reproduction. The scientific and economic experiment was carried out in 2021–2022 at LLC Meat Union of Bashkir Producers, located in the Kuyurgazinsky District of the Republic of Bashkortostan. Indicators of live weight dynamics, live weight gain, relative growth rate, body measurements and body composition indices in the age aspect were studied. Research of the weight growth of young animals of various genotypes made it possible to identify significant differences in terms of absolute and average daily gain in live weight for the entire period of growing and fattening between bulls of the 1st and 2nd experimental groups, respectively, by 32.5 kg and 59.7 g (in both cases – by 6.2 %). The highest values of measurements, indicating the formation of meat qualities and body shape, were noted in bulls of the 1st group compared with peers of the 2nd and 3rd experimental groups. Breeding animals for a long period under different housing and feeding technologies influences the characteristics of the growth and development of the descendants of local reproduction of Limousin breed cattle.

Influence of stimulating basics on the level of iron in the blood of Saanen kids

Goat milk is becoming increasingly attractive for the food sector due to some advantages compared to cow milk: it has higher fat content, protein levels, magnesium, potassium, phosphorus, cobalt, vitamins B1, B2, C, and some amino acids. The Saanen breed is the most attractive for farms since, along with the qualitative superiority of milk, this breed is characterized by increased milk yield. Currently, the main goal of research in goat breeding is to preserve and improve animals’ genetic potential under intensive exploitation conditions when any environmental factor (incredibly inadequate feeding) can negatively affect the productive qualities of animals. The period of their prenatal and early postnatal ontogenesis is especially significant. One of the critical indicators of metabolic processes in the body of young animals is iron, which enhances oxidative processes and promotes the reproduction of erythrocyte hemoglobin. The study showed the influence of the age factor on an increase in the concentration of iron in the blood and better absorption of iron in the presence of copper in the body. The effectiveness of using an iron-containing preparation in combination with protein hydrolysate, a source of protein necessary for the formation of enzymes and hormones involved in regulating iron metabolism in the body, has been noted.

Cytokine and immunoglobulin profiles of Arbor Acres broiler chickens at different stages of physiological development.

Modern scientific research focuses on a detailed study of the immune system, the mechanisms of immunosuppression, and the search for an effective means to restore disturbed immune homeostasis in farm animals. The present study examined the cytokine and immunoglobulin (Ig) profiles of healthy broiler chickens during physiological development. Arbor Acres broilers (n = 28) were used in the study to achieve this objective. The immune status of broiler chickens was assessed on 7, 14, 28, and 42 days of age, including serum levels of cytokines, Igs, and lysozyme by enzyme immunoassay. We observed a decrease in the efficiency of immune system functioning of birds with increasing age. The most pronounced immunological deficiency in the body of broiler chickens is noted at the age of 7-14 days, which is associated with immaturity of the immune system and is characterized by the fact that non-specific humoral and specific cellular defense factors are at a rather low level. The levels of lysozyme, interleukin (IL)-2, IL-10, and IgA in blood serum at this age were minimal; starting from 28 days of age, there is a specific humoral immune deficiency, which is compensated by strengthening of cellular defense factors. The serum level of IgY intensively decreases against the background of an increase of lysozyme, IL-2, IL-4, and IL-10. During postnatal ontogenesis, the immune system of broiler chickens undergoes dynamic changes that have an age direction and phase character. Changes in the immune system may affect immunocompetence, disease susceptibility, and, consequently, productivity.

ULTRASTRUCTURAL FEATURES OF CARDIOMYOCYTE CONTRACTILE APPARATUS IN RAT OFFSPRING HEARTS FOLLOWING MATERNAL CHRONIC ALCOHOL INTOXICATION

Background. The mechanisms underlying the development of the heart contractile apparatus and the distribution of myofibrils in cardiomyocytes following intrauterine ethanol intoxication continue to be a topic of significant debate. The aim of this paper is to determine the dynamics of postnatal changes in the ultrastructure of ventricular contractile cardiomyocytes in the rat heart after chronic alcoholization of the maternal organism. Methods. The study focused on the hearts of rat offspring from birth to adulthood. Transmission electron microscopy was utilized to examine the ultrastructure of cardiomyocytes in various zones of the ventricular myocardium. Results. It has been observed that prenatal alcohol exposure induces cardiomyocyte heteromorphism, characterized by varying degrees of damage throughout postnatal ontogenesis in rat offspring. Specifically, cells exhibiting critical signs of destruction in the myocardium of intramural and subepicardial zones of both ventricles aggregate into clusters surrounded by morphologically intact cardiomyocytes, while irreversibly damaged cells with subendocardial localization appear isolated. Following birth, there is a progressive accumulation of mitochondria exhibiting signs of limited functional activity. These polymorphic organelles, featuring a matrix of moderate or low electron density with sporadically developed cristae, primarily concentrate in paranuclear regions and are dispersed along the interstices of myofibril dissociation. Conclusion. Maternal chronic alcohol intoxication results in enduring harm to the contractile apparatus of ventricular cardiomyocytes in rat offspring. This damage manifests as sarcomere structure disorganization, myofibril fragmentation and misalignment, notable suppression of sarcomerogenesis, and reduced myofibril content, all closely linked to mitochondrial alterations.

The role of cellular polyploidy in the regeneration of the cirrhotic liver in rats and humans.

Polyploidy is a condition in which a cell has multiple diploid sets of chromosomes. Two forms of polyploidy are known. One of them, generative polyploidy, is characteristic of all cells of the organism, while the other form develops only in some somatic tissues at certain stages of postnatal ontogenesis. Whole genome duplication has played a particularly important role in the evolution of plants and animals, while the role of cellular (somatic) polyploidy in organisms remains largely unclear. In this work we investigated the contribution of cellular polyploidy to the normal and the reparative liver growth of Rattusnorvegicus (Berkenhout, 1769) and Homosapiens Linnaeus, 1758. It is shown that polyploidy makes a significant contribution to the increase of the liver mass both in the course of normal postnatal development and during pathological process.

Tissue Interactions in Dense Tissues of the Orofacial Region in Patients with Connective Tissue Dysplasia.

This study aimed to investigate the rate and quality of maturation of the mineral component of impacted teeth 38 and 48 and a fragment of the human lower jaw with connective tissue dysplasia (CTD) in different periods of postnatal ontogenesis. The study involved 102 males (76 with CTD and 26 without CTD), divided into age groups: 31-40, 41-50 and 51-60 years. For medical reasons, teeth 38 and 48 were removed from each patient, as well as a fragment of the alveolar part of the lower jaw in the projection of teeth 38 and 48 measuring 0.5 × 0.5 cm. The odontological parameters, the mineral density of the enamel and the lower jaw, the length and width of the enamel prisms, the spatial organisation of collagen fibrils and the dimensions of the bone plates of the lower jaw were determined. A decrease in optical density was observed at the age of 41-50 and 51-60 years with dysplasia, which indicated a decrease in mineral density and the presence of total areas of hypomineralisation relative to the age of 31-40 years. In the age groups of 41-50 and 51-60 years, pronounced sclerosis and deformation of the delimiting elements were observed at the border of the connective tissue structures and the periosteum. At the age of 31-40 years, the level of stratification of the bone plates was local; after 40 years, it was generalised. Progressive osteoporosis of the lower jaw and incomplete amelogenesis are obstacles to the correct and harmonious eruption of the lower 'wisdom' teeth after 30 years.