Thickness Of Muscle Fibers Research Articles

Features of the microstructure of the quadriceps femoral muscle of broiler chickens of the smena-9 cross with various feeding diets

The article presents the results of studies of the histological and ultrastructural characteristics of the quadriceps femoral muscle of broiler chickens of the Smena-9 cross on the 35th day of postembryonic ontogenesis using feed additives (probiotic, prebiotic, sorbent) of domestic production in addition to the basic feeding diet.The work was implemented within the framework of the thematic task plan for the implementation of research works under the state order of the Ministry of Agriculture of the Russian Federation (Agreement No. 082-03-2023-238 dated 30.01.2023) on the topic: "Development of theoretical foundations and methodology for the practical use of morphological criteria in assessing the quality and safety of poultry products." It has been shown that against the background of the use of feed additives, an increase in the weight of chickens occurs. At the same time, the microstructure of the rectus head of the quadriceps femoris of birds of the control and experimental groups, while maintaining the general plan of structure (the presence of muscular and connective tissue components, bundle organization), is not the same. Based on studies using light and transmission electron microscopy, it was shown that the signs of morphological maturity of skeletal muscle tissue are most pronounced when using a probiotic, in the case of using a prebiotic and a sorbent, muscle fibers grow less synchronously, which is manifested by the variability of their thickness. The thickness of muscle fibers, their bundles, the state of the mitochondrial apparatus, the packing density of myofibrils and their thickness, the degree of development of endomysium and perimysium and the presence of white adipose tissue can be objective morphological and morphometric criteria for assessing the condition of muscle tissue, which correlates with the taste qualities of poultry meat. Data on the structural organization of the quadriceps muscle of the new domestic cross expand the theoretical base in the field of the myology of farm birds, including in terms of identifying morphological signs of the realization of genetic potential against the background of the use of different feeding diets in chicken rearing technology, which allows us to quickly assess the effectiveness of chicken rearing technology and predict an increase in productivity.

454 Utilization of Adipose-Derived Stem Cells in Cranial Nerve Regeneration: A Systematic Review

INTRODUCTION: Large peripheral nerve injuries may require surgical reconnection. Cell-based therapies have also been investigated for nerve regeneration. METHODS: PubMed and Embase databases were used to search for primary studies reporting the use ADSCs in the regeneration of cranial nerves. A total of 12 studies were included which all presented data on specific neural injury, therapy, and functional outcomes. RESULTS: Eight studies focused on the facial nerve (66.7%), two on the optic nerve (16.7%), one on the olfactory nerve (8.3%), and one on the hypoglossal nerve (8.3%). One study applied ADSCs to human cranial nerve injuries, while the remainder studied animal models. In these studies, ADSC groups had higher numbers of myelinated fibers, increased myelin thickness and diameter of muscle fibers as well as greater magnitude of compound muscle action potentials (CMAP) when compared to controls. In studies focused on optic nerve regeneration, significant improvements across visual tests were observed. CONCLUSIONS: ADSCs demonstrate potential utility in regard to their ability to facilitate functional recovery of cranial nerves in humans as well as animal models. Further investigation into the use of ADSC should be pursued in both animal and early human studies to validate the findingsof previous literature.

Moderating AKT signaling with baicalein protects against weight loss by preventing muscle atrophy in a cachexia model caused by CT26 colon cancer

Cancer cachexia is a type of energy-wasting syndrome characterized by fatigue, anorexia, muscle weakness, fat loss, and systemic inflammation. Baicalein, a flavonoid with bioactive properties, has demonstrated the ability to mitigate cardiac and skeletal muscle atrophy in different experimental settings. This effect is achieved through the inhibition of muscle proteolysis, suggesting its potential in preserving skeletal muscle homeostasis. In this study, we investigated the anti-cancer cachexia effects of baicalein in the regulation of muscle and fat wasting, both in vivo and in vitro. Baicalein attenuated body weight loss, including skeletal muscle and white adipose tissue (WAT), in CT26-induced cachectic mice. Moreover, baicalein increased muscle fiber thickness and suppressed the muscle-specific ubiquitin-protease system, including F-box only protein 32 and muscle RING-finger protein-1, by activating AKT phosphorylation both in vivo and in vitro. The use of LY294002, a particular inhibitor of AKT, eliminated the observed impact of baicalein on the improvement of muscle atrophy. In conclusion, baicalein inhibits muscle proteolysis and enhances AKT phosphorylation, indicating its potential role in cancer cachexia-associated muscle atrophy.

Светооптические, ультраструктурные и морфометрические изменения в поверхностной грудной мышце цыплят-бройлеров кросса «Смена-9» при различных рационах кормления

The article presents the results of research on light-optical, ultrastructural and micromorphometric features of the superficial pectoral muscle in broiler chickens of the cross Smena-9 at different feeding rations on the 35th day of ontogenesis. The work was realized within the framework of the thematic plan-assignment for the performance of research work under the state order of the Ministry of Agriculture of Russia (agreement from 30.01.2023 No. 082-03-2023-238) on the theme: “Development of theoretical foundations and methodology of practical use of morphological criteria in assessing the quality and safety of poultry products”. It is shown that the studied muscle has a typical bundle structure and is differentiated into muscle and connective tissue component (endomysium and perimysium). Muscle fibers contain numerous mitochondria and densely arranged myofibrils, creating the phenomenon of transverse striation typical for skeletal muscle. Along with this, there were revealed signs of strengthening of growth processes against the background of feed additives application, which is manifested by an increase in the thickness of muscle fibers and their bundles and an increase in the number of hemocapillaries compared to the control group. More loose packing of muscle bundles with better development of perimysium and formation of white fatty tissue in it in representatives of experimental groups may indicate a potential improvement in meat flavor compared to the control. Unique data were obtained on the peculiarities of changes in the ultrastructure of muscle fibers in response to the use of feed additives: changes in the number of mitochondria and density of myofibrils in the sarcoplasm. All this indicates the biological efficiency of the studied feed additives and morphological “responsiveness” and plasticity of birds of the studied cross to the change of diet by changing the internal structure of muscle as an organ. The obtained data can be used as morphological criteria at complex estimation of meat products of poultry farming during commodity and veterinary-sanitary examination, and also have prospects for further developments on perfection of domestic meat crosses of chickens.

Гистологические показатели мышц цыплят-бройлеров при применении в рационе кормовых добавок

The article presents the results of studying the effect of feed additives «HitAcid» and «Veleguard BG» on the histological parameters of the muscles of broiler chickens of the Ross-308 cross. The study was conducted at the Department of Parasitology and Veterinary and Sanitary Expertise of the Federal State Budgetary Educational Institution of Higher Education «Moscow State Academy of Veterinary Medicine and Biotechnology – MVA named after K. I. Skryabin». During the study, it was found that the use of additives «HitAcid» and «Veleguard BG» stimulate the set of live weight of broiler chickens, and show an increase in the set of muscle mass of carcasses. Indicators of the thickness of muscle fibers and bundles of muscle fibers of the quadriceps femoris and superficial pectoral muscle of broiler chickens of the experimental groups exceed those of the control group. In a comparative assessment of the micromorphometric parameters of the studied muscles, the greatest thickness of muscle fibers and bundles of muscle fibers was noted in the experimental group «HitAcid». The data obtained indicate the expediency of using food additives based on organic acids in the diet of broiler chickens.

Study of the specific features in the histological structure of the longissimus muscle dorsi in animals of the genus <i>Ovis</i>

Relevance. Interspecific hybridization of domestic animals with wild related species is considered as one of the promising directions in animal husbandry in the framework of improving the quality and nutrient biodiversity of livestock products. The article shows the research results of the specific features in the histological structure of the longissimus muscle dorsi in animals of the genus Ovis with different genotypes.Methods. The object of research was sheep of the Romanov breed and interspecific hybrids of domestic sheep (Romanov breed) with argali. Histological studies of the longissimus dorsi muscle of purebred and hybrid animals at the age of 12 months were carried out in a comparative aspect. The thickness and area of muscle fibers, muscle bundles, the number of muscle fibers per unit cross-sectional areas were studied.Results. Differences in a number of morphometric parameters in the main structural units of the longissimus dorsi muscle in hybrid animals depending on the genotype were revealed. In hybrid animals, in comparison with purebred sheep, a decrease in the thickness and area of muscle fibers by 12% and 25% was found (p < 0.01). An increase in the number of muscle fibers per 1 mm2 of the cut and a decrease in the proportion of connective tissue in the structure of the longissimus dorsi muscle in interspecific hybrids were shown in comparison with those in sheep of the Romanov breed (p < 0.01). These biological features of hybrid animals should be taken into account when breeding, selecting and using them to obtain meat and meat products.

Морфологическая характеристика поверхностной грудной мышцы цыплят- бройлеров кросса «Смена-9» при различных рационах кормления

The article presents the results of studies of the structural features of the superficial pectoral muscle in broiler chickens of the Smena-9 cross with various feeding diets on the 35th day of ontogenesis, carried out within the framework of the thematic plan-tasks for the implementation of research works by state order of the Ministry of Agriculture of Russia on the topic: «Development of theoretical foundations and methodology for the practical use of morphological criteria in assessing the quality and safety of poultry products». It is shown that the studied muscle has a typical bundle structure and is differentiated into a muscular and connective tissue component (endomysium and perimysium). Along with this, signs of increased growth processes were revealed against the background of the use of feed additives, which is manifested by an increase in the thickness of muscle fibers and their bundles and an increase in the number of hemocapillaries compared with the control group. A looser packing of muscle bundles with a better development of perimysium and the formation of white adipose tissue in it in representatives of the experimental groups may indicate a potential improvement in the taste qualities of meat compared to the control. The obtained data can be used as morphological criteria for a comprehensive assessment of poultry meat products during commodity and veterinary-sanitary expertise, and are also important for further developments to improve domestic chicken meat crosses

Микроморфология поверхностной грудной мышцы у кур кросса Хайсекс белый на 14-е и 17-е сутки эмбриогенеза

The microstructural characteristics of the muscle tissue of the superficial pectoral muscle in 14 and 17-day-old embryos of Haysex white cross chickens are presented. The described stage of embryogenesis corresponds to the fetal period of embryo development, accompanied by active growth of internal organs while maintaining allantoid respiration. Studies have shown that the thickness of bundles of muscle fibers and perimysium during embryogenesis (from 14 to 17 days) increases while the thickness (diameter) of muscle fibers and the thickness of the endomysium decrease. The area of muscle tissue significantly increases in relation to connective tissue (from 41% to 62%). The results obtained indicate the peculiarities of the formation of skeletal muscles on the 14th and 17th days of embryogenesis in chickens of the egg direction of the productivity of the Haysex white cross, which can be the basis for the formation of a descriptive characteristic of the cross and serve as a criterion for the prognostic assessment of the productive potential of the bird. When conducting scientific research using chickens of various productivity directions, this information can serve as a differential for determining the distinctive features of crosses and breeds in certain periods of embryogenesis for improving breeding and genetic technologies in poultry farming.

Влияние кормовой добавки на основе растительных экстрактов на гематологические показатели и структурное оформление скелетной мускулатуры цыплят-бройлеров

The materials of studies of the effect of the phytobiotic biostimulator «Aferr» (production of SIBAF LLC, Novosibirsk) in the composition of diets on the micromorphological organization of muscle tissue and hematological parameters of broiler chickens of the «Cobb-500» cross are presented. The issues related to changes in biochemical parameters of blood serum and histological structure of muscle fibers of the superficial pectoral muscle of birds reared for 42 days are considered The feed additive used to a certain extent affects the micromorphometric parameters of the skeletal muscles of the studied birds, depending on the dosage used. According to most of the studied parameters characterizing the structure of muscle tissue, such as the thickness (diameter) of muscle fibers, their bundles, perimysium, endomysium, the experimental group receiving a lower dosage was ahead of the control group and the group receiving a higher dosage of phytobiotic. The study showed the ambiguity of the results of the use of phytobiotics in relation to zootechnical indicators, hematology results and in relation to histostructures of the superficial pectoral muscles of the studied groups of birds. The information obtained can be used by specialists in breeding poultry and in assessing the productive qualities of poultry when improving production technologies.

Особенности строения поверхностной грудной мышцы на 14-е сутки эмбриогенеза у кур пород брама и орловская ситцевая

The micromorphological organization of the superficial pectoral muscle in 14-day-old embryos of Brama chickens (meat direction of productivity) and Orlovskaya sitcevaya (egg direction of productivity) is shown. According to most of the studied indicators characterizing the structure of muscle tissue, such as the thickness (diameter) of muscle fibers, their bundles, perimisium, as well as the total area of muscle tissue, Brama is ahead of the Orlovskaya sitcevaya. The exception is the thickness of the endomysium and the number of muscle fibers in the field of view of the microscope in the superficial pectoral muscle. The study of myogenesis in chickens of meat and egg productivity allows us to form the concept of structural features of the muscles of individual breeds and crosses in separate stages of the development of the organism. The information obtained can be used by breeders in breeding poultry and in assessing the productive qualities of poultry while improving production technologies.

Гистологическое строение четырехглавой мышцы бедра в постнатальном онтогенезе у кур мясного направления продуктивности

The article presents the structural features of the organization of the quadriceps femoral muscle in chickens of the meat direction of productivity of the Cobb-500 and Smena-8 crosses on the 29th day of ontogenesis. The quadriceps femoral muscle in the studied period of bird ontogenesis is formed by muscle fibers differentiated from each other by the endomysium and assembled into bundles, between which the perimysium is located. Transverse striation is clearly visualized in the structure of muscle fibers. Studies have revealed the predominance of indicators of the thickness of muscle fibers and perimysium in chickens of the Smena-8 cross over the Cobb-500 cross, the reverse picture is established for indicators of the thickness of bundles of muscle fibers and endomysium. According to the results of the conducted research, information of interest was obtained both in the fundamental aspects of veterinary biology of poultry, in particular, the concept of morphogenesis of the organism of chickens, and in applied significance for the poultry industry, which is reflected in the decoding of the mechanism of formation of skeletal muscles in the studied crosses and the potential use of these results in breeding work.

АНАТОМО-ГИСТОЛОГИЧЕСКИЕ ПАРАМЕТРЫ МЫШЦ ЦЫПЛЯТ-БРОЙЛЕРОВ ПРИ ИСПОЛЬЗОВАНИИ В РАЦИОНЕ КОРМОВОЙ ДОБАВКИ «МАКСИСОРБ®» С ЦЕЛЬЮ ПРОФИЛАКТИКИ МИКОТОКСИКОЗОВ

The article presents the results of a study of the influence of the MaxiSorb® feed additive on the anatomical and histological parameters of the muscles of broiler chickens with chronic mycotoxicoses. It was found that the feed additive has a beneficial effect on the growth and development of poultry, promotes the growth of muscle tissue in chickens. The parameters of the thickness of muscle fibers and of the bundles of muscle fibers of the quadriceps femoris and superficial pectoral muscles of the experimental groups exceed those of the control groups. The data obtained indicate the expediency of using the MaxiSorb® feed additive in the diet of broiler chickens.

Effects of oral contraceptive use on muscle strength, muscle thickness, and fiber size and composition in young women undergoing 12 weeks of strength training: a cohort study

BackgroundIt is suspected that hormonal fluctuations during menstruation may cause different responses to strength training in women who use oral contraceptives (OC) versus those who do not. However, previous studies that investigated the existence of such differences produced conflicting results. In this study, we hypothesized that OC use has no effect on muscle strength and hypertrophy among women undergoing strength training. Thus, we compared the differences in muscle strength and thickness among women who used OCs and those who did not.MethodsWe investigated the influence of OC use on muscle strength (Fmax), muscle thickness (Mtk), type 1-to-type 2 muscle fiber (NO) ratio, muscle fiber thickness (MFT), and nuclear-to-fiber (N/F) ratio. Seventy-four healthy young women (including 34 who used OCs and 40 who did not) underwent 12 weeks of submaximal strength training, after which Fmax was evaluated using a leg-press machine with a combined force and load cell, while Mtk was measured using real-time ultrasonography. Moreover, the NO ratio, MFT, and N/F ratio were evaluated using muscle needle biopsies.ResultsParticipants in the non-OC and OC groups experienced increases in Fmax (+ 23.30 ± 10.82 kg and + 28.02 ± 11.50 kg respectively, p = 0.073), Mtk (+ 0.48 ± 0.47 cm2 and + 0.50 ± 0.44 cm2 respectively, p = 0.888), Fmax/Mtk (+ 2.78 ± 1.93 kg/cm2 and + 3.32 ± 2.37 kg/cm2 respectively, p = 0.285), NO ratio (type 2 fibers: + 1.86 ± 6.49% and − 4.17 ± 9.48% respectively, p = 0.169), MFT (type 2 fibers: + 7.15 ± 7.50 µm and + 4.07 ± 9.30 µm respectively, p = 0.435), and N/F ratio (+ 0.61 ± 1.02 and + 0.15 ± 0.97 respectively, p = 0.866) after training. There were no significant differences between the non-OC and OC groups in any of these parameters (p > 0.05).ConclusionsThe effects of 12 weeks of strength training on Fmax, muscle thickness, muscle fiber size, and composition were similar in young women irrespective of their OC use.

THE MORPHOLOGICAL ADAPTATION OF HEART STRUCTURES AND BIOCHEMICAL BLOOD PARAMETERS OF ROSS-308 BROILER CHICKENS WHEN INTRODUCING THE «KOVELOS-SORB» SORBENT INTO THE MAIN DIET

Background. Currently, the poultry industry is developing quite intensively, this is why the use of various additives that accelerate growth and improve the quality of products is associated with this. The biologically active additive «Kovelos-Sorb» has similar properties – an enterosorbent based on particles of amorphous silicon dioxide.
 Purpose. To study the features of morphological adaptation of heart structures and biochemical blood parameters of Ross-308 broiler chickens when introducing the «Kovelos-Sorb» sorbent into the main diet.
 Materials and methods. Two groups of Ross-308 broiler chickens were studied from 1 day to 40 days, with a total number of 160 heads from 8 age groups of 10 individuals each. The experimental group of chickens was injected with the sorbent «Kovelos-Sorb» in the amount of 0.1% by weight of feed to the main diet. The study of morphological and biochemical parameters of the broiler organism was carried out according to generally accepted methods.
 Results. The analysis of the dynamics of changes in the morphological structures of the heart (linear measurements – longitudinal size, transverse size, girth, thickness of the epicardium, myocardium, endocardium, thickness of muscle fibers), the volume of cardiomyocyte nuclei, biochemical blood parameters of Ross-308 broiler chickens when added to the main diet of the enterosorbent «Kovelos-Sorb».
 Conclusion. It was found that the silicon-containing sorbent «Kovelos-Sorb» has a positive effect on the qualitative morphological characteristics of the heart of Ross-308 broiler chickens, manifested by stabilization of shell structures, in an increase in the thickness of the muscle fibers of the atria and ventricles of the heart.

MORPHOMETRIC INDICATORS OF THE MEMBRANES OF THE VAGINAL PROCESS OF THE PERITONEUM IN CHILDREN OF DIFFERENT AGE GROUPS

Background. According to statistics, such diseases as inguinal hernia, testicular hydrocele are the causes of infertility. The anatomical basis for the occurrence of these nosologies is a violation of the process of obliteration of the processus vaginalis of the peritoneum. It was found that the presence of smooth muscle elements in its wall is the morphological basis for the preservation of patency in the processus vaginalis of the peritoneum. Aim. The purpose of the work was to improve scientific data on the etiology of diseases that occur as a result of the violation of the obliteration of the processus vaginalis of the peritoneum, with further use of the obtained knowledge to improve the quality of surgical correction of pathological conditions. Materials and methods. Children with diagnosed inguinal hernias and testicular hydrocele were treated surgically (Duhamel and Ross operations were performed). During the surgical correction, the wall fragments of the processus vaginalis of the peritoneum were selected for further histological examination. The obtained samples of histological preparations were studied in order to evaluate the morphometric criteria. Morphometric analysis criteria: relative area of muscle tissue, relative area of adipose tissue, relative area of fibrous tissue, thickness of muscle fibers, cross-sectional area of muscle fiber. Results. All children were divided into groups by gender and age. In each age group (first year of life, first three years of life, first five years of life and first seven years of life) an increase in both relative and absolute morphometric indicators was observed. The same tendency of the results was observed in both the male and female parts of the studied children. Conclusions. Therefore, the probability of independent obliteration of the processus vaginalis of the peritoneum increases inversely proportionally with the age of the child, that is, the younger the age of the child, the greater the probability of independent obliteration of the processus vaginalis of the peritoneum.

Morphometric indicators of the membranes of the vaginal process of the peritoneum in children of different age groups

Background. According to statistics, such diseases as inguinal hernia, testicular hydrocele are the causes of infertility. The anatomical basis for the occurrence of these nosologies is a violation of the process of obliteration of the processus vaginalis of the peritoneum. It was found that the presence of smooth muscle elements in its wall is the morphological basis for the preservation of patency in the processus vaginalis of the peritoneum. Aim. The purpose of the work was to improve scientific data on the etiology of diseases that occur as a result of the violation of the obliteration of the processus vaginalis of the peritoneum, with further use of the obtained knowledge to improve the quality of surgical correction of pathological conditions. Materials and methods. Children with diagnosed inguinal hernias and testicular hydrocele were treated surgically (Duhamel and Ross operations were performed). During the surgical correction, the wall fragments of the processus vaginalis of the peritoneum were selected for further histological examination. The obtained samples of histological preparations were studied in order to evaluate the morphometric criteria. Morphometric analysis criteria: relative area of muscle tissue, relative area of adipose tissue, relative area of fibrous tissue, thickness of muscle fibers, cross-sectional area of muscle fiber. Results. All children were divided into groups by gender and age. In each age group (first year of life, first three years of life, first five years of life and first seven years of life) an increase in both relative and absolute morphometric indicators was observed. The same tendency of the results was observed in both the male and female parts of the studied children. Conclusions. Therefore, the probability of independent obliteration of the processus vaginalis of the peritoneum increases inversely proportionally with the age of the child, that is, the younger the age of the child, the greater the probability of independent obliteration of the processus vaginalis of the peritoneum.

Формирование поверхностной грудной мышцы и четырехглавой мышцы бедра у кур мясного направления продуктивности в эмбриогенезе

Morphological and histological characteristics of the quadriceps femoral muscle and the superficial pectoral muscle in chickens of the meat productivity direction (Brama and Smena-8) on the 14th day of embryogenesis are shown. In the studied muscles, muscle fibers were identified, delimited by the endomysium and combined into bundles, between which the perimysium lies. There is no transverse striation in the muscle fibers. In the structure of the skeletal muscles of the Smena-8 cross, the division of muscle fibers into thin and thick is established. During the study, the thickness of muscle fibers and their bundles, as well as the thickness of the endomysium and perimysium were determined. According to all the studied micromorphometric indicators of the quadriceps femoral muscle and the superficial pectoral muscle, the superiority of the Smena-8 cross over the Brama breed was revealed. The presented results indicate the peculiarities of the formation of skeletal muscles on the 14th day of the embryonic period of development of the organism in chickens of the meat productivity direction, which allows using this information in predicting the productive qualities and genetic potential of crosses and breeds involved in breeding work, including in the comparative aspect. In addition, these data expand the concept of histogenesis of skeletal muscles in various representatives of poultry and can be basic in the issues of their assessment by morphological indicators in certain periods of life.

Особенности эмбрионального развития скелетных мышц у кур пород Брама и Юрловская голосистая

The article presents the histological and morphological characteristics of skeletal muscles (quadriceps femoris and superficial pectoral muscle) in meat (Brama) and egg (Yurlovskaya golosistaya) chickens of productivity on the 14th day of embryonic development: formed muscle fibers combined in bundles, as well as endomysium and perimysium, in the absence of transverse striation. The quadriceps femoral muscle of the Brama breed (meat productivity direction) surpasses the Yurlovskaya golosistaya (egg productivity direction) due to thicker muscle fibers collected in compact bundles and thin connective tissue components. The superficial pectoral muscle has no significant differences in most of the studied micromorphological parameters (thickness of muscle fibers, endomysium, area of muscle tissue and the number of muscle fibers in the field of view) in both breeds of chickens. The exception is the thickness of the bundles of muscle fibers in the superficial pectoral muscle of the Brama compared to the Yurlovskaya golosistaya, as well as a well-developed perimysium. The results obtained are basic in the formation of the concept of histogenesis of skeletal muscles in the embryonic period of development of the organism of poultry of various productivity directions and can be used.

Особенности развития скелетных мышц у кур породы Юрловская голосистая в эмбриогенезе

The article presents the histological and morphological characteristics of skeletal muscles (quadriceps femoris and superficial pectoral muscle) in chickens of the egg production direction of the Yurlovskaya Golosistaya breed on the 14th and 20th days of embryonic development. By the 14th day of embryogenesis, formed muscle fibers combined into bundles, as well as endomysium and perimysium, in the absence of transverse striation, were noted in the studied muscles. Skeletal muscle tissue by the 20th day of embryogenesis is characterized by a close to definitive structural organization – in muscle fibers, transverse striation is clearly visible, their bundles are identified, as well as endomysium and perimysium. The superficial pectoral muscle in most of the morphometric parameters studied (the thickness of muscle fibers, their bundles and the representation of the connective tissue component) exceeds the quadriceps, with the exception of the thickness of the endomysium, which on the 20th day prevails in the quadriceps femoral muscle compared to the superficial pectoral muscle. The results obtained are basic in the formation of the concept of skeletal muscle histogenesis in poultry of egg productivity and can be used by specialists in improving the technologies of breeding work.

Сравнительная характеристика четырехглавой мышцы бедра в постнатальном онтогенезе у кур Кобб‑500 и Юрловская голосистая

Histological and morphological characteristics of skeletal muscles in chickens of the meat productivity direction Cobb-500 and egg productivity direction Yurlovskaya golosistaya on the 8-th and 20-th days of postembryonic development were studied. The skeletal striated muscle tissue of the studied bird obeys the general principles of myogenesis inherent in most animal species and is characterized by signs of a definitive structure. It is shown that on the 8-th and 20-th days of postembryonic ontogenesis, the quadriceps femoral muscle of the Yurlovskaya golosistaya breed is ahead of the Cobb-500 cross in terms of the thickness of muscle fibers, while the opposite pattern is established in terms of the thickness of muscle fiber bundles, as well as endomysium and perimysium in the connective tissue component. The area of muscle tissue and the number of muscle fibers in the field of vision in the studied periods of ontogenesis prevail in digital values in Cobb-500 compared to the Yurlovskaya golosistaya. Based on the obtained morphometric parameters of muscle fibers, the concept of histogenesis of skeletal muscles in poultry of egg and meat productivity directions is presented.