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The periovarian vascular complex (PVC) participates with the local transfer of ovarian hormones from venous and lymphatic effluent into the arterial blood supplying the ovary. Nitric oxide (NO) plays an important role in ovarian steroidogenesis, angiogenesis and in the regulation of the blood flow. The aim of the present study was to determine if unilateral progesterone (P₄) infusions to the ovarian artery in the follicular phase of the estrous cycle in pigs may change the activity of NADPH-diaphorase (NADPH-d), marker for NOS, and immunoreactivity (IR) of endothelial nitric oxide synthase (eNOS) and inducible (iNOS) isoforms in the PVC arteries and veins. P₄ was infused into the right (experimental PVC) and the saline was infused into the left ovarian artery (control PVC). The doses of P₄ were: 84 ng/min, 2×84 ng/min and 3×84 ng/min on the first, second and third day of the experiment, respectively. Seven days following the final P₄ infusion gilts were sacrificed and both PVC were stained using histo- and immunohistochemistry methods. In comparison with the control PVC, these infusions of P₄ caused in the experimental PVC: decrease (P < 0.001) of NADPH-d activity and IR of eNOS in the arterial and vein’s endothelium, and in the arterial muscular layer. An increase (P < 0.001) of NADPH-d activity and IR of eNOS, iNOS was observed in the vein’s muscular layer. These results indicate that P₄ change IR NOS isoforms and, consequently, the production of NO. Nitric oxide may be involved in the local control of periovarian vascular complex contractility.
Progesterone (P4), which is produced in the corpus luteum, determines the timing of the estrous cycle and pregnancy in many species. The physiological effect of P4 upon target cells is mediated through interaction of this hormone with two specific nuclear progesterone receptor isoforms (PR-A and PR-B), but also through non-genomic mechanisms. The non-genomic action of P4 has been found in the cells of a number of tissues, including in the female reproductive tract. However, the nature of this mechanism is still unknown. It has been determined that P4 can directly affect enzyme activity, nonspecificly change the membrane fluidity which affects receptor stability or it can bind specific membrane receptors for P4, which stimulate early intracellular signaling pathways and initiate the specific cellular response. There are at least three different proteins localized in the cell membrane, which can be a potential membrane progesterone receptor. This paper presents the latest data concerning the intracellular and membrane progesterone receptor and the genomic and non-genomic action of P4 in the female reproductive tract.
The objective of the examinations performed on 230 cows and 36 embryo recipients was to establish if 1—3 doses of progesterone applied between the 17th and 19th day after insemination or on the 10th day after embryo transfer help the stabilization of pregnancy. After one dose of P4 (250 mg) 51,1% of conceptions were noted, after 2 doses 63,8% and after 3 doses 76,6% of conceptions were observed. In a control group 30,3% of the cows became pregnant. In embryo recipients after one anpplication of an exogenous progesterone at a dose of 125 mg the pregnancy rate was 44,4% as compared to a control group in which the rate was 27,8%. In pregnant cows initial levels of progesterone varied from 1,96 to 8,1 ng/ml. In the group of cows receiving 1 dose of P4 an average increase of the level of progesterone was by 1,1 ng/ml, in the group receiving two injections by 3,36 ng/ml, and in the group receiving three injections of P4 by 4,9 ng/ml. In the control group on the 19th day after insemination in 37,2% of pregnant cows the level of progesterone in blood plasma decreased by an average of 1,65 ng/ml. It can be assumed that the application of exogenous progesterone in inseminated cows with subclinical disturbances of endometrial functions and in embryo recipients positively affects the stanilization of pregnancy.
It is recognized that in cattle there are two physiological, yet morphologically different, forms of corpora lutea (CL): homogeneous ones and those with a cavity. Because of its resemblance to a luteal cyst, a corpus luteum with a cavity may be a significant diagnostic problem. In this article, the author aims to present essential historical and current knowledge of this form of the corpus luteum, from the first analyses in which it was discovered, through extensive CL population studies of the late twentieth century, to theories prevailing in recent years. The conception rates reported by authors cited in this text are compared for both homogeneous and cavitary CL. The article also gives the percentage of cavitary CL in the population, their mean size and concentrations of progesterone secreted. The relationship between the occurrence of CL with a cavity and cows’ fertility is described. The article also presents criteria suggested for the size classification of cavitary CL and the most important information about the occurrence of cavitary CL.
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