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The development of the yellow body and ovarial vesicles was evaluated in 20 cows during an entire oestrus cycle (group II, n = 9) and an oestrus ended by pregnancy (group I, n = 11) using a linear ultrasonograph (5 MHz). The investigations were performed on the first day of oestrus and then on the 5, 12 and 18 day after oestrus. The maximum diameter of the yellow body was noted on the 12th day of the oestrus cycle. At the same time (depending on the phase of oestrus) 25 (40%) of the yellow bodies possessed a vesicle situated internally. This phenomenon did not affect either the length of oestrus or the effects of insemination. At the same time in the group of pregnant cows the size of the yellow body with a vesicle was on the 12th day significantly larger than in group II (p < 0,05). A large vesicle was observed with a similar frequency in both groups of cows in 30, 50 and 75% of the animals on the 5, 12 and 18 day of the cycle, respectively. The large size of the vesicle observed on the 5th day of oestrus suggests that it is a vesicle which dominates the first period of growth of the ovarial vesicles.
In terms of its anatomy and functions, the reproductive system of birds is significantly different from the one found in mammals. It consists of only the left ovary and the left oviduct, which is constantly exposed to ascending infections because of its connection with the cloaca. Hence, the proper functioning of humoral and cell-mediated local immune mechanisms in this system is very important for maintaining its physiological functions. The expression of Toll-like receptors and the presence of T and B lymphocytes have been demonstrated in both the ovary and the oviduct of chickens. CD4⁺ T cell subpopulation is distributed mainly in the lamina propria of the oviduct, whereas in the submucous membrane and muscular layer these cells are found less frequently. CD8⁺ T lymphocytes are equally distributed in all abovementioned layers of the oviduct wall. IgY⁺ B cells are distributed among the epithelial cells, and they are closely connected with the glandular tissue of the oviduct, mainly in the infundibulum, magnum, and uterus regions. IgA⁺ and IgM⁺ B cells are present in the entire oviduct, but mainly in the glandular tissue of the magnum. IgY⁺ B cells have not been detected in the ovary, unlike IgM⁺ B cells, which have been demonstrated in the ovary stroma. In addition to T and B cells, antigen-presenting cells are present in the follicle wall and in the oviduct. During the early stages of reproductive maturation, a decrease in the number of immunocompetent cells is observed in the reproductive system, and the local immnosuppression increases the susceptibility of birds to Salmonella Enteritidis infections. The number of T and B lymphocytes in the mucous membrane of the oviduct decreases with age, which facilitates infections of the reproductive system. Additionally, the local immune mechanisms of the reproductive system in birds involve the transfer of protective IgY, IgA and IgM maternal antibodies to hatching eggs. The local immune mechanisms of the reproductive tract are responsible for preventing infections that disturb the physiological functions of the reproductive system and for protecting eggs from contamination.
Oestrus status without standing reflex is enumerated among the typical clinical signs of zearalenone mycotoxicosis in sexually immature gilts. The aim of the study was to assess the influence of a low dose of zearalenone applied per os for 7 days on the morphometric results of the organs of the reproductive system in sexually immature gilts that were and that were not subjected to ovariectomy. Zearalenone and α-zearalenole were determined in blood plasma with the common use of separation methods with the columns of immunological affinity and high performance liquid chromatography with fluorescent detection. Tissues of the reproductive system were taken directly after the slaughter (on day 8 of the experiment) for morphometric examinations. The study was carried out on twelve 4 months old gilts, at 38-45 kg of body weight. The results obtained showed that per os application of zearalenone at a dose of 200 µg /kg b.w. for 7 days evoked signs of apparent sexual readiness without standing reflex in gilts after ovariectomy and in physiologically efficient gilts. The level of α-zearalenole had been significantly increased and zearalenone had been noted in blood serum before these signs appeared. Double and triple enlargement of the uterus was noted in both experimental groups. The mass and volume of the ovaries in physiologically efficient gilts diminished about 50%.
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