1,720,990 research outputs found
Quality Control of Boar Sperm Processing: Implications from European AI Centres and Two Spermatology Reference Laboratories
Get PDFIn recent years, increased automatization has resulted in a higher efficiency of boar semen processing in AI laboratories. Sophisticated laboratory management and efficient quality control programmes are needed for current tendencies in major pork-producing countries to reduce the sperm number per AI dose, to lengthen semen storage times and to adopt responsible methods for bacterial control and prevention of the development of multiresistant bacteria. The objective of the present review was to outline current trends in boar semen production and the critical steps in semen processing which affect sperm quality. In addition, integrated elements of a quality assurance programme in use by thirty European AI centres in association with the two German spermatology reference laboratories are described
The Role of Conceptus-maternal Signalling in the Acquisition of Uterine Receptivity to Implantation in Mammals
No full textImplantation is a pivotal step in the establishment of mammalian pregnancy. Although implantation strategies vary between species, many aspects of conceptus-maternal signalling necessary to induce uterine receptivity to implantation are conserved. The temporal 'window' for the initiation of implantation is short and precisely controlled by endocrine, paracrine and autocrine factors. An invariable prerequisite for the development of uterine receptivity to implantation is continuous exposure of the endometrium to progesterone which, after a species-specific interval, downregulates progesterone receptor (PGR) expression in the epithelium and stimulates the production of progestamedins. Uterine receptivity involves temporal changes in the expression of genes, leading to modifications in surface, extracellular matrix and secretory characteristics that support growth, proliferation, migration and attachment of the conceptus. Moreover, a complex interplay between endometrial progestamedins and estramedins and conceptus-derived oestrogens, cytokines and interferons (INFs), prostaglandins (PGs) and cortisol is crucial to the preparation for implantation. Understanding the individual roles and combined actions of conceptus and endometrial autocrine and paracrine factors in the development of uterine receptivity to implantation is essential for translational research into strategies to reduce pregnancy loss in man and animals
Impact of porcine circovirus type 2 (PCV2) vaccination on boar semen quality and quantity using two different vaccines
No full textPorcine circovirus type-2 (PCV2) is widespread in domestic pig populations. It can be shed with boar semen, but the role boars have in epidemiology is still unclear. Vaccinating boars against PCV2 can reduce disease and virus load in semen, but may have unwanted side effects, that is, impairment of spermatogenesis. Therefore, the aim of this study was to investigate the effect and impact of two different PCV2 vaccines on boar semen quality and quantity. Healthy normospermic Large White boars in three groups of 12 each were vaccinated with either Circovac, Ingelvac CircoFLEX, or received NaCl. Eight ejaculates were collected starting 1 week after vaccination and assessed for quantitative traits. In general, sperm quantity and quality parameters did not change due to the vaccination (P > 0.05). Only DNA integrity between the Circovac and control group was P < 0.05 but remained at a low level (<2%). One boar showed clinical signs with body temperature up to 39.9 °C and went off feed. For this animal, a clear relation between vaccination, fever period, and impaired sperm quality could be observed. The results indicate that both vaccines did not have a major impact on sperm quality or quantity. Therefore, vaccination of boars against PCV2 seems to be feasible. However, one boar treated with the oil-based vaccine showed a temporarily impaired semen quality after elevated body temperature after vaccination. Thus, possible systemic reactions and the subsequent impact on sperm quality should be taken into account when choosing a PCV2 vaccine for boars
Usefulness of bovine and porcine IVM/IVF models for reproductive toxicology
No full textWomen presenting fertility problems are often helped by Assisted Reproductive Techniques (ART), such as in vitro fertilization (IVF) programs. However, in many cases the etiology of the in/subfertility remains unknown even after treatment. Although several aspects should be considered when assisting a woman with problems to conceive, a survey on the patients' exposure to contaminants would help to understand the cause of the fertility problem, as well as to follow the patient properly during IVF. Daily exposure to toxic compounds, mainly environmental and dietary ones, may result in reproductive impairment. For instance, because affects oocyte developmental competence. Many of these compounds, natural or synthetic, are endocrine disruptors or endocrine active substances that may impair reproduction. To understand the risks and the mechanism of action of such chemicals in human cells, the use of proper in vitro models is essential. The present review proposes the bovine and porcine models to evaluate toxic compounds on oocyte maturation, fertilization and embryo production in vitro. Moreover, we discuss here the species-specific differences when mice, bovine and porcine are used as models for human
Gastrulation and the establishment of the three germ layers in the early horse conceptus.
No full textExperimental studies and field surveys suggest that embryonic loss during the first 6 weeks of gestation is a common occurrence in the mare. During the first 2 weeks of development, a number of important cell differentiation events must occur to yield a viable embryo proper containing all three major germ layers (ectoderm, mesoderm, and endoderm). Because formation of the mesoderm and primitive streak are critical to the development of the embryo proper, but have not been described extensively in the horse, we examined tissue development and differentiation in early horse conceptuses using a combination of stereomicroscopy, light microscopy, and immunohistochemistry. Ingression of epiblast cells to form the mesoderm was first observed on day 12 after ovulation; by Day 18 the conceptus had completed a series of differentiation events and morphologic changes that yielded an embryo proper with a functional circulation. While mesoderm precursor cells were present from Day 12 after ovulation, vimentin expression was not detectable until Day 14, suggesting that initial differentiation of mesoderm from the epiblast in the horse is independent of this intermediate filament protein, a situation that contrasts with other domestic species. Development of the other major embryonic germ layers was similar to other species. For example, ectodermal cells expressed cytokeratins, and there was a clear demarcation in staining intensity between embryonic ectoderm and trophectoderm. Hypoblast showed clear α1-fetoprotein expression from as early as Day 10 after ovulation, and seemed to be the only source of α1-fetoprotein in the early conceptus
Oviduct Binding and Elevated Environmental pH Induce Protein Tyrosine Phosphorylation in Stallion Spermatozoa
No full textSperm-oviduct binding is an essential step in the capacitation process preparing the sperm for fertilization in several mammalian species. In many species, capacitation can be induced in vitro by exposing spermatozoa to bicarbonate, Ca2+, and albumin; however, these conditions are insufficient in the horse. We hypothesized that binding to the oviduct epithelium is an essential requirement for the induction of capacitation in stallion spermatozoa. Sperm-oviduct binding was established by coincubating equine oviduct explants for 2 h with stallion spermatozoa (2 × 106 spermatozoa/ml), during which it transpired that the highest density (per mm2) of oviduct-bound spermatozoa was achieved under noncapacitating conditions. In subsequent experiments, sperm-oviduct incubations were performed for 6 h under noncapacitating versus capacitating conditions. The oviduct-bound spermatozoa showed a time-dependent protein tyrosine phosphorylation response, which was not observed in unbound spermatozoa or spermatozoa incubated in oviduct explant conditioned medium. Both oviduct-bound and unbound sperm remained motile with intact plasma membrane and acrosome. Since protein tyrosine phosphorylation can be induced in equine spermatozoa by media with high pH, the intracellular pH (pHi) of oviduct explant cells and bound spermatozoa was monitored fluorometrically after staining with BCECF-AM dye. The epithelial secretory cells contained large, alkaline vesicles. Moreover, oviduct-bound spermatozoa showed a gradual increase in pHi, presumably due to an alkaline local microenvironment created by the secretory epithelial cells, given that unbound spermatozoa did not show pHi changes. Thus, sperm-oviduct interaction appears to facilitate equine sperm capacitation by creating an alkaline local environment that triggers intracellular protein tyrosine phosphorylation in bound sperm
Validating reference microRNAs for normalizing qRT-PCR data in bovine oocytes and preimplantation embryos
Get PDFBACKGROUND: MicroRNAs (miRNAs) are small noncoding RNAs that act as post-transcriptional regulators of gene targets. Accurate quantification of miRNA expression using validated internal controls should aid in the understanding of their role in epigenetic modification of genome function. To date, most studies that have examined miRNA expression levels have used the global mean expression of all expressed genes or the expression of reference mRNAs or nuclear RNAs for normalization. RESULTS: We analyzed the suitability of a number of miRNAs as potential expression normalizers in bovine oocytes and early embryos, and porcine oocytes. The stages examined were bovine oocytes at the germinal vesicle (GV) and metaphase II stages, bovine zygotes, 2, 4 and 8 cell embryos, morulae and blastocysts, as well as porcine cumulus oocyte complexes, GV, metaphase I and II oocytes. qRT-PCR was performed to quantify expression of miR-93, miR-103, miR-26a, miR-191, miR-23b, Let-7a and U6 for bovine samples and miR-21, miR-26a, miR-93, miR-103, miR-148a, miR-182 and miR-191 for porcine oocytes. The average starting material for each sample was determined using specific standard curves for each primer set. Subsequently, geNorm and BestKeeper software were used to identify a set of stably expressed miRNAs. Stepwise removal to determine the optimum number of reference miRNAs identified miR-93 and miR-103 as the most stably expressed in bovine samples and miR-26a, miR-191 and miR-93 in porcine samples. CONCLUSIONS: The combination of miR-93 and miR-103 is optimal for normalizing miRNA expression for qPCR experiments on bovine oocytes and preimplantation embryos; the preferred combination for porcine oocytes is miR-26a, miR-191 and miR-93
Mare and foal survival and subsequent fertility of mares treated for uterine torsion
Get PDFREASONS FOR PERFORMING STUDY: Previous surveys have reported mare and foal survival after correction of uterine torsion varies from 60-84% and 30-54%, respectively. Furthermore, resolution via a standing flank laparotomy (SFL) has been associated with better foal, but not mare, survival. OBJECTIVES: To compare the success of SFL with other correction methods (e.g. midline or flank laparotomy under general anaesthesia; correction per vaginam). STUDY DESIGN: Retrospective analysis of clinical records. METHODS: Data on correction technique, stage of gestation, degree of rotation, survival and subsequent fertility for 189 mares treated for uterine torsion (UT) at 3 equine referral hospitals in the Netherlands during 1987-2007 were analysed. RESULTS: Mean stage of gestation at diagnosis was 283 days (range 153-369) with the majority of UTs (77.5%) occurring before Day 320 of gestation. After UT correction, 90.5% of mares and 82.3% of foals survived to hospital discharge, between 3 and 39 days later, and to foaling. Multivariable logistic regression indicated that correction method and stage of gestation at UT affected survival of foals and mares. For foals, survival was 88.7% after SFL compared to 35.0% after other methods (P = 0.001). When UT occurred at <320 days, 90.6% of foals survived, compared to 56.1% at ≥320 days (P = 0.007). For mare survival, an interaction between stage of gestation and correction method was detected (P = 0.02), with higher survival after SFL (97.1%) than other methods (50.0%) at <320 days of gestation (P<0.01). When UT occurred at ≥320 days, mare survival did not differ between techniques (76.0% vs. 68.8; P = 0.6). Of 123 mares that were bred again, 93.5% became pregnant; fertility did not differ between mares treated by SFL (93.9%) and other techniques (87.5%; P = 0.9). CONCLUSIONS: SFL is the surgical technique of choice for resolving uncomplicated (i.e. no co-existing gastrointestinal lesions) equine UT except when the stage of gestation exceeds 320 days
Effect of alternate day collection on semen quality of Asian elephants (Elephas maximus) with poor initial fresh semen quality
Get PDFIn captivity, male Asian elephants often yield poor quality semen after transrectal manually assisted semen collection; however, the reasons for the disappointing semen quality are not clear. Here we test the hypothesis that accumulation of senescent spermatozoa is a contributory factor, and that semen quality can therefore be improved by more frequent ejaculation. To this end we investigated the effect of collecting semen five times on alternate days, after a long period of sexual rest, on semen quality in Asian elephants known to deliver poor semen during infrequent single collections. All eight bulls initially displayed a high incidence of detached sperm heads and low percentages of motile (close to 0%) spermatozoa. After semen collection on alternate days, the percentages of detached sperm heads, and head and mid-piece abnormalities, were reduced significantly (p<0.05). In particular, one bull showed markedly improved sperm motility (increased from 0% to 60%) and membrane integrity (increased from 5% to 75%). In addition, advancing age significantly (p<0.01) correlated with lower percentages of sperm with intact membranes and a higher frequency of detached sperm heads. In contrast to sperm accumulation problems in other species, a small ampullary diameter correlated significantly (p<0.05) with reduced semen quality
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