Morphohistochemical study of the rat placenta administered a hepatotropic poison at different periods of pregnancy]

Intragastric administration of CCl4 (0.3 ml per 100 g of body weight) to female rats caused a marked injury of the placental tissue and particularly of the chorionic epithelium of the labyrinthine portion with the maximal development of dystrophic necrobiotic processes on the 14th-16th day of pregnancy (when the poison was administered 48 hours before the animal was sacrificed). There was noted an increase in the number of mitoses in the epithelial cells at all the periods, and a statistically significant enlargement of the nuclei and the nucleoli of the cytotrophoblastic cells on the 17th--18th day of the intrauterine fetal development. CCl4 administration led to the reduction in the content of histochemically detectable glycogen in the cytoplasm of the chorionic epithelium and to the fall in the amount of amylase-resistant glycoproteins, protein and RNA in dystrophically altered cells.     

Muscle tissue regeneration of the lymph hearts in adult Rana temporaria frogs. A study by light and electron microscopy autoradiography methods

The regeneration response of adult frog lymph heart muscle tissue was studied from 2 to 3 weeks after mechanical injury. High resolution autoradiographic studies showed that regenerative necrotic zones have many actively proliferating mononuclear cells deprived of cytoplasmic myofilaments. Some of them have numerous free ribosomes, so they might be identified as myoblasts. On the 13th day after injury newly-formed myotubes with chains of myonuclei and pictures of active sarcomerogenesis were observed. On the other hand, the surviving muscle fibers of the perinecrotic zone were rich in myonuclei at their growing ends. In the vicinity of nuclei, accumulation of a mass of non-differentiated cytoplasm rich in free ribosomes and polysomes, rough endoplasmic reticulum, Golgi apparatus, and centrioles are seen. Tritiated thymidine pulse-labeling showed that only rare myonuclei of the perinecrotic zone muscle fibers were labeled, whereas numerous non-differentiated cells of granulation tissue and myosatellites incorporated thymidine. The number of labeled myonuclei markedly increased 96 hours after 3HTdr administration. These data evidence that the myoblastic mechanism is predominant in the regeneration of adult frog lymph heart muscle tissue. It is necessary to emphasize that during the lymph heart muscle tissue reparative myogenesis some of the perinecrotic myonuclei are able to synthesize DNA and to divide mitotically, which distinguishes this type of muscle from skeletal muscle tissue of vertebrates.     

Features of the structure of the mesenteric and tracheobronchial lymph nodes in rat offspring after exposure to tetracycline

Ante- and postnatal development of anatomical structures and cells of lymphatic nodes has been studied in rat offspring subjected to tetracycline effect during placentation and organogenesis (the 8th-14th days) and during fetogenesis (the 15th-20th days). Tetracycline injection during the 8th-14th days of embryogenesis results in certain disturbances of the nodular structure formations, inhibition of lympho- and plasmo-cytopoesis against the background of a sharp increase in number of basophilic granulocytes and tissue basophils. The antibiotic effect on the 15th-20th days of embryogenesis does not disturb the lymph node formation, but produces an increasing number of lymphocytes, plasmocytes, macrophages, eosinophilic granulocytes and tissue basophils in them.     

Myocardial reaction of the right ventricle to lung resection

Right-sided pulmonectomy (resection of 63-65% of the lung parenchyma) in white noninbred rats resulted in development of chronic cor pulmonale, that develops according to the stages: I--from the time of the operation up to the 10th-15th days after the operation--the stage of acute disturbances and mobilization forces of the organism; II--from the 11th-15th up to the 90th day is the stage of a relative steady compensatory hypertrophy of the cardiac right ventricle; III--after the 90th day--the stage of decompensation. The hypertrophy of the right ventricle myocardium transfers into its dilatation. Amount of cardiomyocytes and their nuclei in 1 mg of the right ventricle tissue progressively decreases, quantity of multinuclear cardiomyocytes increases, ploidy of the nuclei changes: number of tetraploid nuclei decreases, octaploid nuclei appear. Lethality among the animals is 56%.     

Divergent differentiation during embryonal histogenesis of skeletal muscle tissue

Morphometric analysis of the developmental processes of the satellite cells and myosimplasts has been performed in embryonal histogenesis of the skeletal muscle tissue in 17 human fetuses 8-27 weeks of the intrauterine development. The sequence of death of some myoblasts in embryonal histogenesis is described in details. Basing on the data obtained, a conception on existance of muscular-proliferative units (MPU) in composition of the skeletal muscles is put forward. The amount of the MPU determines the whole number of muscle fibers in the muscle. The anlage of the MPU occurs as a result of divergent differentiation of the stem myogenic cells at early stages of myogenesis (myosimplasts and myotubes) from the cells commited to mutual fusion. The fund of these cells is determined by the number of myogenic elements that are at the state of the proliferative rest. One of the mechanisms regulating the number of the resting cells is the growth rate of the simplast lengthwise. The resting cells, appearing at late stages of myogenesis (of the muscle fibers), are the sources for development of the myosatellites in mature muscle fibers. In dying myotubes there is a sharp disturbance in growth processes lengthwise, in biosynthesis of contractile proteins, in correlation between the number of nuclei in the satellite cells and those of simplasts.     

Embryonic chicken gizzard: immunolocalization of collagen and smooth muscle myosin

Summary Antibodies to chicken gizzard myosin and to chicken skin collagen type I allow the myofibrillar and connective tissue development in the embryonic chicken gizzard to be followed. Fibroblasts are assumed to synthesize collagen prior to the onset of smooth muscle cell development in the muscle primordium (day 5); they are presumably also responsible for collagen synthesis close to the presumptive lamina propria and in the developing tubular glands (day 14 to 17). From day 6 to 8, myosin and collagen are colocalized intracellularly, and from day 9 onward collagen fibers start to appear extracellularly, eventually forming the trellis-like connective tissue septa that give the rhomboid profile found in the adult muscle. The close association of collagen and myosin in early development suggests that the muscle cells themselves produce and export collagen.     

Time of origin of cells in the histiogenesis of the spinal cord]

In order to establish the moment of appearance of neuroblasts and ectoglia of the spinal cord the autoradiographic study with the use of H3-thymidine and C14-thmidine injected to pregnant mice with the intervals between injections 121/2 or 24 hours was undertaken. It was establised that spinal neurons were removed from the nervous tube beginning from the 10th up to 13th days of embroyogenesis. The motoneurons of the anterior horn were the first to appear (10th-12th days), the neurons of the intermideate zone were the next to appear (11th - 12th days) and the last were the neurons of posterior horn (13th day). Beginning from the 13th day of embryogenesis there appeared the ectoglia which migrated following meurblasts two days later. The saturation of the grey matter with glial cells and the saturation of the white matter with Schwann cells was brought about by means of additional multiplication at the site of the glioblasts removed from the nervous tube. The main function of the matrix layer neuroepithelium of the nervous tube as a provider of cells to the spinal cord terminated on the 15th day of embryogenesis.     

Interrelations of cyclic adenosine monophosphate and calcium in regulating glycogen synthetase in developing skeletal and cardiac muscles in chickens]

The decrease of glycogen synthetase activity under the effect of Ca++ and cAMP is observed in the skeletal muscles of chick embryos only at the later stages of embryogenesis (15-18 days). In the cardiac muscle the activity of glycogen synthetase is inhibited by Ca++ apparently prior to the 12th day of development, long before the effect of cAMP which appears, as in the skeletal muscles, on the 18th day. Under the combined effect of cAMP and Ca++ in vitro and that of Ca++ and epinephrine in vivo, no additivity was observed. The possibility of Ca++ participation in the realization of catecholamine effect on the glycogen synthetase system of muscle and their interrelations with cAMP are discussed.     

Changes in cyclic AMP, adrenylate cyclase and protein kinase levels during the development of embryonic chick skeletal muscle.

The levels of cyclic AMP (cAMP) and activities of adenylate cyclase and protein kinase have been examined in chick skeletal muscle tissue between the 7th and 15th day of its embryonic development. The tissue cAMP levels were found to increase in two main phases; from 8–10 days and from 12–15 days of development. Parallel increases between the 8th and 10th day of development were also found in the basal enzyme activities of both adenylate cyclase and protein kinase. The maximum values of all three parameters coincided with the onset of cell fusion in the tissue. The results are compared with the findings of a similar study carried out on differentiating myoblasts cultured in vitro, and are assessed in terms of the possibility that cAMP levels control the expression of myoblast differentiation.     

Development of the thoracic duct in the prenatal period of human ontogeny

In 40 series of histological sections performed in human embryos and prefetuses from 4 up to 20 weeks of development, as well as in 20 corpses of fetuses and stillborns, it has been stated that the anlage of the thoracic duct appear in 6-7-week-old fetuses as lymphatic clefts surrounded with mesenchymal cells that are situated near large veins in the areas of the most active morphogenesis. Connecting with each other, the clefts form the jugular and retroperitoneal lymph sacs and a well branching network of canals. From the latter, on the 7th-8th week of development a plexus of lymph vessels appear, and later on (on the 8th-9th week)--bilaterally situating trunks of the thoracic duct. Further development of the thoracic duct is connected with the lymph nodes formation, their germs appear on the 9th-10th week along the course of the left trunk, as well as along the ductal branches and anastomoses. The formation of the lymph nodes results in reduction of some trunks and plexuses of the thoracic duct. Owing to this, its form in 14-15-week-old prefetuses resembles the one in newborns. Disturbances in the formation processes of the lymph nodes along the course of the reducing ductal areas, as well as their formation along the course of its main trunk can result in various structural variants of the thoracic duct in children and grown-up persons. Histogenesis of the thoracic duct wall and formation of the lymph nodes are not completed by birth.     

Differentiation of human pancreatic endocrinocytes during embryogenesis

Time of appearance, succession and ultrastructural peculiarities of pancreatic endocrinocytes have been studied in human embryogenesis. A-insulocytes (the 7th-8th week) appear before B-endocrinocytes (the 9th-10th week). Before the 10th week A-insulocytes possess a higher degree of cytodifferentiation and development of the mechanisms necessary for hormones secretion. This should be taken into account at allotransplantation of the embryonal pancreas with the aim to correct insulin insufficiency.     

Lack of negative regulation of beta-adrenoreceptor affinity by guanine nucleotides in embryonic membranes and its induction by the GTP-binding protein from mature protein

The negative regulation of the beta-adrenoreceptor affinity by guanine nucleotides in the sarcolemmal fraction of chicken skeletal muscle at different stages of ontogenesis was studied. It was found that the negative regulation is absent in the embryonic period; the effect of GTP is manifested only before hatching, whereas that of Gpp(NH)p--at later periods, i.e., in 1-month-old chickens. Similar age-dependent dynamics was revealed with respect to the GTP effect on the dissociation rate of the [3H]DHA-beta-adrenoreceptor complex. An addition to the system containing embryonic muscle membranes of the GTP-binding protein isolated from skeletal muscle and liver of chickens whose age exceeds 20 days led to earlier manifestations of the above effects (on the 13th-15th embryonic days). The data obtained testify to the limiting role of GTP-binding proteins in the negative control of the hormone-receptor interaction and support the authors' hypothesis on the absence in the embryonic muscle of the 42 kD GTP-binding protein responsible for the functional coupling of the hormone-sensitive adenylate cyclase components.     

Reorganization of peptidergic systems during brain regeneration in Eisenia fetida (Oligochaeta, Annelida)

After the extirpation of the brain reorganization of the peptidergic (FMRFamide, neuropeptide Y, proctolin) systems was studied in the newly forming cerebral ganglion of the annelid Eisenia fetida. During regeneration, all immunoreactive fibres appear on the 1st-2nd postoperative day. At the beginning of regeneration, immunoreactive neurons and fibres form a mixed structure in the wound tissue. On the 3rd postoperative day, FMRFamide positive and neuropeptide Y-immunoreactive, while on the 7th postoperative day proctolin-immunoreactive neurons appear in the loose wound tissue. From the 25th postoperative day a capsule gradually develops around it. The neurons of the preganglion move to the surface of the newly appearing preganglion. The number of these cells gradually increase, and by the 72th-80th postoperative days the localization and number of peptide-immunoreactive neurons is similar to that in the intact one. The neurons of all examined peptidergic systems may originate from the neuroblasts, situated on the inner and outer surface of the intact ganglia (e.g. suboesophageal and ventral cord ganglia). In addition FMRFamide and proctolin immunoreactive neurons may take their derive by mitotic proliferation from the pharyngeal neurons, too.     

Granulocyte-colony stimulating factor enhances muscle proliferation and strength following skeletal muscle injury in rats.

Insufficiency of skeletal muscle regeneration often impedes the healing process with functional deficiencies and scar formation. We tested the hematopoietic growth factor granulocyte-colony stimulating factor (G-CSF) with respect to its efficacy to improve functional muscle regeneration following skeletal muscle injury in Wistar rats. After crush injury to the left soleus muscle, animals received daily G-CSF (20 mug/kg ip) or vehicle solution (n = 30 per group each). Sham-operated animals without muscle injury served as controls (n = 15). After in vivo assessment of the fast-twitch and tetanic contraction capacity of the soleus muscles at days 4, 7, and 14 post-injury, sampling of muscle tissue served for analysis of satellite cell proliferation [bromodeoxyuridine (BrdU)/laminin and BrdU/desmin double immunohistochemistry] and cell apoptosis (transferase nick-end labeling analysis). Muscle strength analysis revealed recovery of contraction forces to 26 +/- 2, 35 +/- 3, and 53 +/- 3% (twitch force) and to 20 +/- 3, 24 +/- 2, and 37 +/- 2% (tetanic force) within the 14-day observation period in vehicle-treated animals. In contrast, G-CSF increased contractile forces with markedly higher values at day 7 (twitch force: 42 +/- 2%; tetanic force: 34 +/- 2%) and day 14 (twitch force: 62 +/- 3%; tetanic force: 43 +/- 3%). This enhancement of muscle function was preceded by a significant increase of satellite cell proliferation (BrdU-positive cells/mm(2): 27 +/- 6 vs. vehicle: 12 +/- 3) and a moderate decrease of cell apoptosis (transferase nick-end labeling-positive cells/mm(2): 11 +/- 2 vs. vehicle: 16 +/- 3) at day 4. In conclusion, G-CSF histologically promoted viability and proliferation of muscle cells and functionally enhanced recovery of muscle strength. Thus G-CSF might represent a therapeutic option to optimize the posttraumatic course of muscle tissue healing.     

Interleukin-15 stimulates adiponectin secretion by 3T3-L1 adipocytes: evidence for a skeletal muscle-to-fat signaling pathway

Interleukin-15 (IL-15) is a cytokine which is highly expressed in skeletal muscle tissue, and which has anabolic effects on skeletal muscle protein dynamics both in vivo and in vitro. Additionally, administration of IL-15 to rats and mice inhibits white adipose tissue deposition. To determine if the action of IL-15 on adipose tissue is direct, the capacity of cultured murine 3T3-L1 preadipocytes and adipocytes to respond to IL-15 was examined. IL-15 administration inhibited lipid accumulation in differentiating 3T3-L1 preadipocytes, and stimulated secretion of the adipocyte-specific hormone adiponectin by differentiated 3T3-L1 adipocytes. The latter observation constitutes the first report of a cytokine or growth factor which stimulates adiponectin production. IL-15 mRNA expression by cultured 3T3-L1 adipogenic cells and C2C12 murine skeletal myogenic cells was also examined. Quantitative real-time PCR indicated IL-15 mRNA was expressed by C2C12 skeletal myogenic cells, and was upregulated more than 10-fold in differentiated skeletal myotubes compared to undifferentiated myoblasts. In contrast, 3T3-L1 cells expressed little or no IL-15 mRNA at either the undifferentiated preadipocyte or differentiated adipocyte stages. These findings provide support for the hypothesis that IL-15 functions in a muscle-to-fat endocrine axis which modulates fat:lean body composition and insulin sensitivity.     

The action of the cells of hemopoietic organs in chick embryos on mouse CFUdc and CLFUdc]

The humoral influence of cells of hemopoietic organs of chicken embryos of different terms on the development of the colony and cluster formation of mononuclears of the bone marrow of mice was studied in joint cultivation in two-compartment cylindrical diffuse microchambers. The process of formation of colonies and clusters is inhibited by cells of the yolk sac on the 2nd-4th day of the development, by cells of the liver on the 8th-12th day, of the spleen on the 13th-18th day and of the bone marrow--on the 15th day. The yolk sac cells were found to have most considerable inhibiting influence on proliferation and differentiation of cells on the 2nd day of the development of chicken embryo. The yolk sac cells on the 6th day stimulate the formation of colonies and clusters. The yolk sac, beginning from the 4th day of the development, and the liver release humoral factors promoting the formation of erythroid colonies. The erythroid colonies are formed but when cultivated on the vascular membrane of the chicken embryo; the erythroid colonies are not formed when cultivated in the abdominal cavity of mice. Local erythropoietinoid factors are not synthetized by the spleen and bone marrow cells. A supposition is put forward that a combination of the local inhibiting and erythropoietic effects promotes the erythroid differentiation of cells.     

Ankyrin repeat and SOCS box protein 15 regulates protein synthesis in skeletal muscle

Ankyrin repeat and SOCS box protein 15 (ASB15) is an Asb family member expressed predominantly in skeletal muscle. We have previously reported that ASB15 mRNA abundance decreases after administration of beta-adrenergic receptor agonists. Because beta-adrenergic receptor agonists are known to stimulate muscle hypertrophy, the objective of this study was to determine whether ASB15 regulates cellular processes that contribute to muscle growth. Stable myoblast C2C12 cells expressing full-length ASB15 (ASB15-FL) and ASB15 lacking the ankyrin repeat (ASB15-Ank) or SOCS box (ASB15-SOCS) motifs were evaluated for changes in proliferation, differentiation, protein synthesis, and protein degradation. Expression of ASB15-FL caused a delay in differentiation, followed by an increase in protein synthesis of approximately 34% (P<0.05). A consistent effect of ASB15 overexpression was observed in vivo, where ectopic expression of ASB15 increased skeletal muscle fiber area (P<0.0001) after 9 days. Expression of ASB15-SOCS altered differentiation of myoblasts, resulting in detachment of cells from culture plates. Expression of ASB15-Ank increased protein degradation by 84 h of differentiation (P<0.05), and in vivo ectopic expression of an ASB15 construct lacking both the ankyrin repeat and SOCS box motifs decreased skeletal muscle fiber area (P<0.0001). Together, these results suggest ASB15 participates in the regulation of protein turnover and muscle cell development by stimulating protein synthesis and regulating differentiation of muscle cells. This is the first study to demonstrate a role for an Asb family member in skeletal muscle growth.     

Reactivity of the smooth muscle tissue of the large intestine under conditions of experimental obstruction]

Morphohistochemical and autoradiographic techniques were used to study the reactivity of the large intestine tunica mascularis under experimental ileus. The smooth muscle cells are subjected to pronounced changes. At early terms (1-2 days) reactive-compensatory reactions are observed. They include increased metabolic processes, hypertrophy of myocytes, their increased synthetic and proliferative activity. Simultaneously there appear degenerative phonomena which become predominant on the 4th-6th days. The level of metabolism in the smooth muscle tissue drops and the synthetic and proliferative activity of myocytes decreases. They undergo atrophy and lyse.