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The aim of the study was to present the scale of use, risk factors and possibilities, which sorter semen gives in biotechnics used in reproduction of cattle. Modern sorters allow for the evaluation of 6 million X and Y spermatozoa per hour. Sex-sorted semen, which is commercially used, contains 2.1 × 106 of spermatozoa. It is used mostly in AI of milk heifers, mainly in large cattle herds. Sorted semen containing Y spermatozoa is sold less often in the world than the one with X spermatozoa. The percentage of the desired sex of the young is higher than 90. The pregnancy rate after application of sorted semen is about 20–25% lower than after insemination of non-sorted semen and depends on a number of factors. The main factors are: breed of female, service number, the herd of origin, the depth of semen deposition, the bull producing semen, ambient temperature and technical parameters during sperm sorting. A number of methods have been developed to improve conception rate, including timed artificial insemination (TAI) and synchronization of heat and ovulation. Results of donor inseminations with the use of sorter semen are presented, with the lower percentage of embryos suitable for the transfer and embryos of the highest quality highlighted. Previous studies do not indicate a reduction of the conception rate after the transfer of embryos obtained in vitro and in vivo after fertilization using sorted semen. It remains difficult to justify a significant increase in the frequency of stillbirths of bulls after using sorted sperm. Similarly, 16% of stillbirths of bulls were observed after embryo transfer, when donors were inseminated with sorter semen. The percentage of stillbirths of bulls after embryo transfer with the use of conventional semen is 9%. The sorted semen is not often used for inseminations in pigs, sheep and goats.
The endometrium of the uterus is a highly dynamic structure in terms of its changes during the various stages of the sexual cycle. These changes are the result of cyclical fluctuations in the concentrations of steroid hormones and local factors of an auto – and paracrine – nature. This condition indicates that the causes of degenerative processes of the uterus must be sought not only in disorders of the hormonal profile and bacterial infections but also disorders at the molecular level. Factors that may play a key role in the formation and development of various pathologies of the female reproductive system include growth factors and their receptors (growth factors – GFs). Discussing these growth factors in the work may provide useful molecular markers that identify pathological conditions of the endometrium. Subject to expression in the endometrium, they are involved in the regulation of cell proliferation, migration and secretion of the glandular epithelium, they also regulate physiological and pathological angiogenesis, revealing strong pro-inflammatory effects. In this research, the authors present an overview of current scientific reports indicating that changes in the expression of studied factors, and thus disturbances in their effects, may constitute one of the causes of pathogenesis within the uterus in many animal species.
The process of spermegg fusion is one of the most important mechanisms involved in successful fertilization. Studies conducted in an effort to elucidate this process are mainly focused on analyzing the interaction between the membrane proteins of male and female gametes. In the last few years, the genes coding proteins which may play an integral role in the process of sperm-egg binding and fusion have been identified. It has been suggested that sperm ADAMs family proteins are involved in this process. The sperm specific fertilin α, fertilin β and cyritestin are among this protein family. The oocyte’s integrins, which are included in egg cell membrane, form receptors specific for those proteins. The other group of proteins, which are connected with sperm-egg fusion, are specific for oocyte CD9 protein and sperm epididymal protein DE. The aim of this review was to present the characteristics of several proteins involved in the sperm-egg interaction process. The exploration of fertilization mechanisms may become the basic element that will improve assisted reproductive techniques and in vitro fertilization in mammals.
It has been clearly demonstrated in several studies that zona pellucida is modificated during oogenesis and folliculogenesis, important stages of mammalian oocytes maturation. However, little is known to date about differential expression and various distributions of proteins involved in fertilization, e.g. zona pellucida glycoprotein 3 (pZP3), integrin-beta-2 (ITGB2) within the porcine oocytes. Since the morphology of the female gamete significantly influences the ability of oocytes for maturation and fertilization, this study aimed to investigate the distribution of pZP3 and ITGB2 in four morphologically different porcine oocytes using confocal microscopic observations. The porcine COC’s were morphologically evaluated in a four graded scale with special relation to colorization of cytoplasm and cumulus cell layers, cultured in culture medium NCSU-23 for 44 h at 38°C, and then subsequently fixed with anti-pZP3 and anti-ITGB2 antibodies, and analyzed using confocal microscopic observations. Consequently, we found that pZP3 protein was localized in oocytes graded as I and II in zona pellucida and cytoplasm. In oocytes graded as III and IV, pZP3 was distributed in the cytoplasm. Regarding the ITGB2, in oocytes graded as I the zona pellucida localization was observed. In the other grades of oocytes a strong cytoplasmic expression of ITGB2 was detected. In conclusion, the expression of both pZP3 and ITGB2 proteins as well as the differential distribution of these proteins within the female gamete are associated with the morphological type of porcine oocytes.
Both epidermal growth factor (EGF) and transforming growth factor (TGF) play an important physiological role in the processes of proliferation and differentiation of several different cell types. However, the expression profiles of these factors in domestic bitches endometrium are still poorly recognized. The aim of the present study was to identify and analyze the differential expression of these factors in various stages of the estrus cycle. Endometrial tissue from proestrus (n=17), estrus (n=10), day 10 diestrus (n=15), day 35 diestrus (n=18) and anestrus (n=25) was collected soon after ovariohysterectomy. Total RNA was isolated from the endometrium by means of Chomczyński and Sacchi method, treated by DNase I, and reverse- transcribed into cDNA. Quantitative analysis of EGF, TGFβ1, TGFβ2, and TGFβ3 cDNA was performed by real-time quantitative polymerase chain reaction (RT-PCR). EGF expression in canine endometrium was increased in the estrus stage as compared to proestrus (P<0.05), day 10 diestrus (P<0.05), day 35 diestrus (P<0.01) and anestrus (P<0.001). We also found the differences in EGF expression between day 10 and day 35 of estrus as well as between day 35 of estrus with anestrus (P<0.05, P<0.01, respectively). The TGFf1 transcript contents were also higher in estrus as compared to other stages (P<0.01). The TGFβ2 and TGFβ3 in the estrus stage was increased compared to proestrus, day 10 diestrus, day 35 diestrus and anestrus (P<0.05). We proved that expression of EGF and TGFβ transcript isoforms is related to the phase of estrus in bitches and therefore may be regulated by specific hormone concentrations during these periods. Our results confirm the hypothesis that these growth factors play a role in the regulation of biochemical changes in the endometrial tissues during the estrus cycle.
Integrins are the major receptors within the extracellular matrix (ECM) that mediate several functions connected with cell life and metabolism, such as cell adhesion, migration, cytoskeletal organization, proliferation, survival, and differentiation. A vascular endothelial growth factor (VEGF) is one of the most important angiogenic factors. It has been suggested that the expression of this gene may play crucial physiological roles in reproductive organs. All investigated endometrial tissues were isolated on day 10-12 after mating. Control bitches, used in this study, were in metestrus, which was determined according to the vaginal cytology and progesterone level in blood. Early pregnancy was verified by flushing the uterine horns with PBS. Total RNA was isolated from the bitches endometrium by means of the Chomczyński and Sacchi method, treated by DNase I, and reverse-transcribed into cDNA. A quantitative analysis of integrins α2b, β2 and β3, VEGF 164, 182 and 188 cDNA was performed by RT-PCR. In results we have shown an increased expression of all investigated genes (integrins α2b, β2 and β3, VEGF 164, 182, and 188) in pregnant bitches uterus as compared to non-pregnant females (P<0.001). Our results indicated that the expression of genes encoding integrins and vascular endothelial growth factors is different in relation to the time of the embryo implantation and it is increased in the first period of this process. This may be associated with the induction of specific mechanisms responsible for receptivity of uterus following the embryo attachment. In addition, all of investigated genes are up-regulated in a pregnancy-specific manner and the increased expression of these genes may regulate the uterus function during the implantation of canine embryos.
The aim of the present study was to investigate whether selected factors attributed to oocyte donors can affect the number and quality of canine cumulus-oocyte-complexes (COC). The following parameters were considered: female age and body mass, ovarian weight, presence of functional ovarian structures (eg. corpus luteum, visible follicles), and ovarian and uterine pathology. Altogether 10 077 COCs were collected, on average 125.6 per bitch. The number and quality of collected COCs was significantly affected by female age and the presence of functional ovarian structures. We found an increased total number of COCs in up to 8-month-old bitches as compared to up-to-3-year-old and up-to-7-year-old females (P < 0.001). Moreover, senile females produced more high quality COCs than the younger ones. However, the differences between those groups were not statistically significant (P = 0.469, P = 0.346). A higher number of COCs was collected from ovaries with a smooth surface (202.8) or with visible follicles (121.1), in comparison to ovaries with corpus luteum (97.6), bitches with pyometra and pathologies of the ovaries or the uterus (82.8). No influence of the bitch’s body mass and ovarian weight on the number of COCs was observed, although a higher number of oocytes was usually collected from the right ovary. The quantity and morphological quality of bitch COCs varied significantly among individual females in an age-dependent manner. The greater number of COCs, isolated from younger bitches, may be associated with a higher reproductive potential and hormonal activity of these females. The study suggests that the age affects the total number of collected COCs but has no influence on the quality of bitch oocytes.
This review presents basic criteria for evaluating the developmental competence of oocytes and embryos, and contains a detailed description of the microfluidic-technology-based Lab-on-Chip. The developmental competence of oocytes is acquired through a complex process associated with oocyte growth and maturation, the storage of large amounts of mRNA and proteins, and with the formation of proper cell morphology. The full maturation of oocytes is required for successful monospermic fertilization and embryonic preimplantation development. The morphology of the gamete is one of the most important factors influencing the developmental competence of the cell. There are several indicators for the assessment of oocyte morphology, most of them including the color and granularity of the cytoplasm. Intensive research is under way to develop and introduce new non-invasive methods of oocyte and embryo quality assessment as a major factor in the improvement of assisted reproductive techniques. The Lab-on-Chip technology, as an independent micro-cytometric device, is a combination of reproductive biology techniques and micro-optic electronics. In the future, Lab-on-Chip systems may be used as an important diagnostic instrument for evaluating the quality of mammalian oocytes and embryos.
This review presents the molecular basis of mechanisms regulating oogenesis and folliculogenesis, as well as the species specificity of these mechanisms and genetic determinants of successful fertilization in pigs. Oogenesis and folliculogenesis are species-specific processes, although several features are common to all mammals. These features are especially visible in the molecular basis of these processes. The most important genetic factors regulating normal oogenesis and folliculogenesis include the transforming growth factor beta (TGFβ) and several other proteins from the TGFβ family. Several experiments have indicated the influence of this gene’s expression on the ability of oocytes to mature, be successfully fertilized, and form a zygote and a blastocyst. However, the regulation of this gene’s expression shows a considerable species specificity. Similarly, mechanisms regulating the fertilization process have several features common to all mammalian species, which is especially conspicuous in the structure of genes that are responsible for fertilization. Two important determinants of fertilization ability are oocyte morphology and follicular size.
The development of assisted reproduction methods requires the application of techniques for the assessment of sperm quality of animals kept for breeding purposes. At present there are a number of methods for the parametric evaluation of spermatozoa, used to determine the reproductive potential of males. Owing to the large number of factors inf1uencing the maturation and capacitation of sperm and the complexity of the fertilisation process, it is difficult to accurately estimate fertilising potential. None of the presently used methods is fully reliable. Conventional laboratory methods, such as the microscopic analysis of the number, mobility, morphology and vitality of spermatozoa or the computer-assisted CASA method, do not provide reliable results as to the functional properties of semen. Most of these methods make it possible to analyse only a single determinant of sperm fertilization potential. High heterogeneity in sperm population makes semen analysis even more difficult. In order to achieve more reliable results, a number of functional analyses are applied, such as flow cytometry, sperm-zona binding tests, HZA and SPA tests. Other such methods include the evaluation of apoptosis and DNA damage as well as acrosome reaction assessment and the use of the molecular marker of spermatozoa. All the above methods make it possible to observe a number of influences and transformations occurring in spermatozoa prior to fertilization. A detailed analysis of the stages by which sperm acquires the ability to fertilize an egg is not only essential for the evaluation of sperm quality, but it is also a source of valuable information on molecular and cellular mechanisms of the fertilization process, some aspects of which still remain elusive.
The development of assisted reproductive technologies (ART) is based on the application of advanced molecular biology and cell biology techniques, including the analysis of gene expression, transcriptional profile and proteomics research of bovine oocytes and embryos. The aim of numerous experiments is to select candidate genes, whose expression and regulation affects the quality of oocytes and embryos. Currently, by using modern techniques of molecular biology it is possible to determine the quality of oocytes in terms of their capacity for maturation, fertilization and proper embryo development in preimplantation stages. However, the molecular genetics methods used for assessing the quality of gametes and embryos are invasive and lead to a partial or complete loss of cell viability. Therefore, it is very important now to search for new, non-invasive methods which would make it possible to analyze several parameters of cells without their destabilization. The lab-on-a-chip system based on the microfluidic technology and recent developments in microengineering constitutes a chemical or biotechnological laboratory in micro scale. The application of this system for the analysis of bovine oocyte and embryo quality represents a fusion between reproductive biology and optoelectronics. To date there has only been scarce research in this area, which has, nevertheless, demonstrated that the analyses based on this system are non-invasive and objective. The analysis of oocyte and embryo quality based on the lab-on-a-chip system, which reveals spectral characteristics of the cells may be an important element in research on their developmental potential. This article presents several aspects of the evaluation of bovine oocyte and embryo quality, including methods used for the analysis of cell developmental potential and competence.
The developmental competence of oocytes and embryos is one of the basic factors in determining whether the oocytes will be able to grow and mature and whether the embryos will be able to develop in the preimplantation stage and implant properly. There are several methods of evaluating the developmental competence of oocytes and embryos. The most frequently used include the oocyte maturity test using brilliant cresyl blue (BCB), and molecular analyses, such as genomics, transcriptomics, and proteomics. The Lab-on-Chip (LOC) system is a microcytometer that analyzes the spectrum of light absorption. The analysis of oocyte and embryo competence with this system concerns the thickness and color of the zona pellucida, as well as the color and granularity of the cytoplasm. The microfluidic chip includes two micro fibers and two channels: one leading in and one leading out. The total measuring system comprises a docking station with a chip, micro-spectrophotometer, and laptop. The system can therefore be used under non-laboratory conditions. Analysis with this system is a new and noninvasive method of bovine and porcine oocyte and embryo quality assessment, and may in the future be one of the main tools used in evaluating the developmental competence of these cells. This article presents the possible function and use of a system based on the microfluidic technology. Moreover, the construction and applications of the LOC are discussed, including the possibilities of LOC application in analyses of the developmental competence of bovine and porcine oocytes and embryos.
Several morphological, molecular and cellular changes lead to the differentiation of primordial germ cells (PGC) into gametes, eggs and spermatozoa. This process is followed by the migration of these cells to gonads and several cell division cycles (mitotic and meiotic) as well as cell differentiations where these cells are changed into fully mature gametes. The process of gametes maturation is composed of several stages of specific biochemical changes that include changes in the nucleus as well as the changes in oocyte’s cytoplasm. The main factor which determines the formation of the developmental competence of oocytes is the long stage of mRNA and proteins storage (cytoplasmic maturation) that plays the main role in the blastocyst formation process. In this article selected issues associated with the regulation of each of the stages of oocytes differentiation as well as their influence of selected factors such as follicular size or formation of oocyte’s transcriptome have been presented. Moreover, a new-noninvasive system of oocytes/embryos quality assessment by using microfluidic techniques was presented.
The development of pig reproductive biotechnology has made it possible to use this species not only as farm animals but also as important models in biomedical research. Systems based on pig embryos from in vitro fertilization (IVF) are used much more frequently, although the quality of these embryos differs from those produced by in vivo fertilization. The most frequent problems in the IVF procedure are disturbances in both nuclear and cytoplasmic oocyte maturation, and the mechanism of polyspermy specific for this species. Although there has been progress in increasing the number of oocytes produced by in vitro maturation processes, the quality of embryos from these oocytes and their developmental competence is still unsatisfactory. It has been suggested that the most important factor in this process is the establishment of optimal conditions for the development and maturation of oocytes. In this review the authors attempt to explain the molecular basis of oocyte maturation, meiosis resumption, and meiotic spindle assembly. The article is also an opportunity to use the knowledge gained to date in order to increase the efficiency of animal breeding, to evaluate the genetic value of oocytes, as well as to improve assisted reproductive techniques (ART).
The process of oocytes maturation in mammals is regulated by the expression of many types of cell-specific genes. Both nuclear and cytoplasmic maturation is based on activation of biochemical and metabolic pathways that lead to reaching the full maturation stage (MII) of oocytes. The most recent data indicates that the proteins belonging to transforming the growth factor beta (TGF-β) superfamily play an important role in the process of oocytes maturation, as well as of reaching full developmental capacity by these cells. Moreover, it has been clearly showed that the proteins belonging to TGF-β such as inhibins (INHA, INHB) and activins regulate both folliculo- and oogenesis by the stimulation and/or inhibition of several biochemical pathways. In this review, the most recent knowledge about the role of proteins belonging to TGF-β superfamily in the regulation of folliculogenesis, oogenesis and oocytes maturation has been presented and discussed.
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