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The aim of the present study was to determine 1) concentrations of NOx in the myometrium of pregnant gilts, and 2) the influence of estradiol-17ß (E2) and/or progesterone (P4) on NOx production by the porcine myometrium on days 5, 10, 15, 20, 25, 30, 35, 40 and 60 of pregnancy (n = 5 per day). Total NOx concentrations were determined using a microplate assay method based on the Griess reaction. During the first 60 days of gestation, a triphasic pattern in the concentration of NOx in the porcine myometrium was observed with a peak on days 10-15, 30 and 60 of gestation. We also demonstrated the stimulatory effect of E2 and/or P4 on in vitro NO production by the porcine myometrium. The stimulatory effect of steroid hormones on NOx release depended on the treatment dose of steroids and day of pregnancy. These data suggest that locally produced NO may inhibit spontaneous uterine contraction and therefore is involved in the maintenance of myometrial quiescence during pregnancy.
The umbilical cord is extremely important for correct fetal development. Just after the porcine umbilical vessels are diversified into arteries and veins, the direct transport of oxygen and nutrients between mother and fetus is possible. The aim of the present study was to determine the histological changes of developing porcine umbilical cord structures on day 40, 60, 75, 90 of pregnancy and after natural delivery by light microscopic observations. In the succeeding analyzed days of pregnancy the authors have observed changes of the umbilical vessels’ size, especially the enlargement of the muscular layer and increase in the size of the lumen. Furthermore, marked transmogrifications were noted in the amniotic and allantoic duct epithelium. The morphological reorganization of umbilical cord elements was relevant with increased concentration of elastic fibres stabilizing umbilical vessels, allantoic duct and amniotic epithelium in mucous connective tissue (Wharton’s jelly). These findings indicate that structural changes observed in the architecture of the porcine umbilical cord seem to be reasonable considering dynamic fetal growth.
This study aimed to evaluate the effect of heat acclimation of neonatal and adult rats on their testes response to in vitro treatment with triiodothyronine (T3). Four groups of rats were housed from birth as: 1) control (CR) at 20°C for 90 days, 2) neonatal heat-acclimated (NHA) at 34°C for 90 days, 3) adult heat-acclimated (AHA) at 20°C for 45 days followed by 45 days at 34°C and 4) de-acclimated (DA) at 34°C for 45 days followed by 45 days at 20°C. Blood plasma and both testes were harvested from 90-day old rats. Testicular slices were then submitted to in vitro treatment with T3 (100 ng/ml) for 8 h. Plasma fT3 level was lower in AHA, NHA and DA groups than in CR group. Basal thyroid hormone receptor α1 (Thra1) expression was higher in testes of NHA and DA and β1 receptor (Thrb1) in DA rats vs. other groups. In the in vitro experiment, T3: 1) decreased Thra1 expression in all groups and Thrb1 in DA group, 2) increased Star expression in CR, NHA and DA groups, and Hsd17b3 expression in NHA group, 3) decreased the expression of Cyp11a1 in NHA and DA groups, and Cyp19a1 in all the groups, 4) did not affect the activity of steroidogenic enzymes and steroid secretion (A4, T, E2) in all the groups. These results indicate, that heat acclimation of rats, depending on their age, mainly affects the testicular expression of steroidogenic enzymes in response to short-lasting treatment with T3.
The purpose of the present study was to determine the immunoreactivity of vascular endothelial growth factor (VEGF) and its two receptors: VEGFR-1 (flt-1, fms-like tyrosine kinase) and VEGFR-2 (flk-1, fetal liver kinase) on the endothelial cells of the lymphatic vessels in the area of the vascular subovarian plexus (VSP) of the broad ligament during different phases of the estrous cycle in pigs. The authors also investigated the expression and correlation between investigated factors and phases of the estrous cycle. The highest immunoreactivity for VEGF-A was observed in the lymphatic vessels of VSP at the follicular and early luteal phases of the estrous cycle. VEGFR-1 displayed the same pattern of immunostaining intensity as VEGF-A and VEGFR-2 revealed the highest immunoreactivity in the early luteal and late luteal phases of the estrous cycle. Additionally, VEGF-A, VEGFR-1 and VEGFR-2 expression was assessed by semi-quantitative Western Blot analysis, which revealed significantly higher levels of VEGF-A and VEGFR-2 proteins during the early-luteal and the follicular phase of the estrous cycle (P ≤ 0.001) and a very weak expression of VEGFR-1 during the whole estrous cycle. All factors displayed phase-related differences in the immunostaining intensity of the endothelial cells of the lymphatic vessels (VSP) in the porcine broad ligament of the uterus, suggesting that they are hormone-dependent during the estrous cycle in pigs.
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