The experiment aimed to compare conventional freezing and different vitrification protocols for cryopreservation of caprine embryos at morphological, ultrastructural, and functional levels. Caprine embryos produced in vivo were allocated randomly to three groups: (1) conventional freezing with ethylene glycol (EG); (2) dimethyl sulfoxide + EG (DMSO/EG) vitrification; and (3) dimethylformamide + EG (DMF/EG) vitrification. All groups were scored for cell viability (propidium iodide staining and ultrastructural levels) and re-expansion rate after thawing or warming. Embryos subjected to DMSO/EG vitrification showed higher cell viability (73.33%), compared with DMF/EG vitrification and conventional freezing group embryos (40.00 and 66.66%, respectively). The ultrastructural study revealed that vitrified embryos had greater preservation of cellular structure than embryos from conventional freezing with EG. DMSO/EG vitrification resulted in higher rates of re-expansion in vitro (47.36%) than DMF/EG vitrification (31.58%), and conventional freezing (25.00%). In conclusion, caprine embryos produced in vivo are better cryopreserved after vitrification than conventional freezing, therefore we conclude that DMSO/EG vitrification is the most effective protocol for cryopreservation.

To determine the effect of undernutrition on embryo production and quality in superovulated sheep, 45 ewes were allocated into two groups to be fed diets that provided 1.5 (control, C; n = 20) or 0.5 (low nutrition, L; n = 25) times daily requirements for maintenance, from oestrous synchronization with intravaginal sponges to embryo collection. Embryos were collected 7 days after the onset of oestrus (day 0). Low nutrition resulted in lower live weight and body condition at embryo collection (P < 0.05). Diet (P < 0.01) and day of sampling (P < 0.001) significantly affected plasma non-esterified fatty acid (NEFA) and insulin concentrations. Plasma leptin concentrations decreased on day 7 only in L ewes. A significant effect of dietary treatment (P < 0.05) and day (P < 0.0001) was observed on plasma insulin-like growth factor (IGF)-I concentrations. The number of recovered oocytes and embryos did not differ between the groups (L: 15.4 ± 0.4; C: 12.4 ± 0.4). Recovery rate was lower (P < 0.05) in the L (60%) than in the C group (73%). The total number of embryos and number of viable-transferable embryos (5.0 ± 0.3 and 3.4 ± 0.3 embryos, respectively) of the L group were lower (P < 0.1) when compared with controls (8.4 ± 0.4 and 6.2 ± 0.4 embryos, respectively). Undernutrition during the period of superovulation and early embryonic development reduced total and viable number of embryos. These effects might be mediated by disruption of endocrine homeostasis, oviduct environment and/or oocyte quality.

Sea urchin embryos initiate cell specifications at the 16-cell stage by forming the mesomeres, macromeres and micromeres according to the relative position of the cells in the animal–vegetal axis. The most vegetal cells, micromeres, autonomously differentiate into skeletons and induce the neighbouring macromere cells to become mesoendoderm in the β-catenin-dependent Wnt8 signalling pathway. Although the underlying molecular mechanism for this progression is largely unknown, we have previously reported that the initial events might be triggered by the Ca2+ influxes through the egg-originated L-type Ca2+ channels distributed asymmetrically along the animal–vegetal axis and through the stretch-dependent Ca2+channels expressed specifically in the micromere at the 4th cleavage. In this communication, we have examined whether one of the earliest Ca2+ targets, protein kinase C (PKC), plays a role in cell specification upstream of β-catenin. To this end, we surveyed the expression pattern of β-catenin in early embryos in the presence or absence of the specific peptide inhibitor of Hemicentrotus pulcherrimus PKC (HpPKC-I). Unlike previous knowledge, we have found that the initial nuclear entrance of β-catenin does not take place in the micromeres, but in the macromeres at the 16-cell stage. Using the HpPKC-I, we have demonstrated further that PKC not only determines cell-specific nucleation of β-catenin, but also regulates a variety of cell specification events in the early sea urchin embryos by modulating the cell adhesion structures, actin dynamics, intracellular Ca2+ signalling, and the expression of key transcription factors.

Genome-editing technologies are considered to be an important tool for generating gene knockout cattle models. Here, we report highly efficient disruption of a chromosomally integrated eGFP gene in bovine somatic cells using RNA-guided endonucleases, a new class of programmable nucleases developed from a bacterial Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 system. In the present study, we obtained homogenously eGFP-expressing primary fibroblasts from cloned bovine transgenic embryonic tissues and employed them for further analysis. CRISPR/Cas9 plasmids specifically targeting the eGFP gene were transfected into the eGFP fibroblasts by electroporation. After 10 days of culture, more than 40% of the cells had lost eGFP expression in fluorescence activated cell sorting (FACS) analysis. Targeted sequences of the transfected cells were analyzed, and various small indel mutations (6–203 bp deletions) in the target sequence were found. The fibroblasts mutated with the CRISPR/Cas9 system were applied for somatic cell nuclear transfer, and the reconstructed embryos were successfully developed into the blastocyst stage. In conclusion, the CRISPR/Cas9 system was successfully utilized in bovine cells and cloned embryos. This will be a useful technique to develop livestock transgenesis for agricultural science.

Balanced reciprocal translocation carriers are usually phenotypically normal. Although the reproductive risk of these carriers varies, they generally have a lower chance to produce normal or balanced gametes. Preimplantation genetic diagnosis (PGD) is offered to these patients to increase their chances of becoming pregnant by selecting a balanced embryo for transfer. This study aimed to analyse the development and the PGD outcome of the embryos obtained from reciprocal translocation carriers focusing on ones with chromosome 10 rearrangements. In total, 27 reciprocal translocation carriers underwent 31 cycles of PGD. PGD was performed using multicolour fluorescence in situ hybridisation for 298 embryos and of these 136 were obtained from couples carrying translocations involving chromosome 10 rearrangements. Carriers of translocations involving chromosome 10 rearrangements have a lower chance of producing normal or balanced embryos compared with the carriers with other rearrangements. The development of embryos obtained from the patients with chromosome 10 rearrangements was impaired and only a limited number of embryos developed to the blastocyst stage.

The aim of this study was to evaluate and to compare testicular tissue in immunized and control boars. Eighteen male piglets, aged 12 weeks, were vaccinated twice intramuscularly with a maltose-binding protein–gonadotropin-releasing hormone I hexamer peptide (MBP-GnRH-I6). Blood samples were taken at 12, 18, 21 and 24 weeks of age. Serum concentrations of testosterone and GnRH-I antibodies were determined by radioimmunoassay. The pigs were sacrificed 6 weeks after the second immunization. Testicular weight and size were recorded and tissue samples were collected for histological examination. The results demonstrated that active immunization against MBP-GnRH-I6 increased serum GnRH-I antibody levels (P < 0.05) and reduced serum concentrations of testosterone (P < 0.05) when compared with controls. Histological studies performed on testicular tissue revealed clear signs of atrophy in the MBP-GnRH-I6 immunized pigs, and a significant reduction (P < 0.05) in paired testes weight and size were seen in the treated boars. Microscopically, the mean diameter of the seminiferous tubules was markedly reduced (P < 0.01). Spermatogonia were visible, as well as few spermatocytes, but no spermatozoa were detected in the seminiferous tubules. Ultramicroscopic analysis of testicular tissue revealed an increase in the thickness of the basement membrane and extensive damage in the cell organelles of the treated animals, including small spermatogonial size, decreased number of mitochondria and endoplasmic reticulum in the primary spermatocyte and spermatid, a shallow hollow for nuclear membranes in Sertoli cells and mitochondrial vacuolation in Leydig cells. We conclude that MBP-GnRH-I6 induces severe atrophy in the testes of immunized boars.

Mature oocytes are arrested in metaphase II due to the presence of high levels of active maturation promoting factor (MPF). After fertilization, active MPF levels decline abruptly, enabling oocytes to complete meiosis II. One of the first and universal events of oocyte activation is an increase in cytosolic Ca2+ that would be responsible for MPF inactivation. Mature oocytes can also be activated by parthenogenetic activation. The aims of this work are to test the ability of dehydroleucodine (DhL) and its hydrogenated derivative 11,13-dihydro-dehydroleucodine (2H-DhL) to induce chemical activation in amphibian oocytes and to study the participation of calcium in the process. Results indicated that DhL and 2H-DhL induced oocyte activation in a dose-dependent manner. After 90 min of treatment, DhL 36 μM was able to induce 95% activation, while 2H-DhL 36 μM was less active, with only 40% activation. Our results suggest that DhL induced the inhibition of MPF activity, probably by an increase in intracellular Ca2+ concentration. Extracellular Ca2+ would not be significant, although Ca2+ release from intracellular stores is critical. In this sense, IP3Rs and RyRs were involved in the Ca2+ transient induced by lactones. In this species, RyRs appears to be the largest contributor to Ca2+ release in DhL-induced activation. Although more studies are needed on the mechanism of action through which these lactones induce oocyte activation in Rhinella arenarum, the results of this research provide interesting perspectives for the use of these lactones as chemical activators in in vitro fertilization and cloning.

In the present study, a porcine system was supplemented with sorbitol during in vitro maturation (IVM) or in vitro culture (IVC), and the effects of sorbitol on oocyte maturation and embryonic development following parthenogenetic activation were assessed. Porcine immature oocytes were treated with different concentrations of sorbitol during IVM, and the resultant metaphase II stage oocytes were activated and cultured in porcine zygote medium-3 (PZM-3) for 7 days. No significant difference was observed in cumulus expansion and the nuclear maturation between the control and sorbitol-treated groups, with the exception of the 100 mM group, which showed significantly decreased nuclear maturation and cumulus expansion. There was no significant difference in the intracellular reactive oxygen species (ROS) levels between oocytes matured with 10 or 20 mM sorbitol and control groups, but 50 and 100 mM groups had significantly higher ROS levels than other groups. The 20 mM group showed significant increases in intracellular glutathione and subsequent blastocyst formation rates following parthenogenetic activation compared with the other groups. During IVC, supplementation with sorbitol significantly reduced blastocyst formation and increased the apoptotic index compared with the control. The apoptotic index of blastocysts from the sorbitol-treated group for entire culture period was significantly higher than those of the partially sorbitol-exposed groups. Based on these findings, it can be concluded that the addition of a low concentration of sorbitol (20 mM) during IVM of porcine oocytes benefits subsequent blastocyst development and improves embryo quality, whereas sorbitol supplement during IVC has a negative effect on blastocyst formation.

There are no studies that document the production of prostaglandins (PGs) or their role in Rhinella arenarum oocyte maturation. In this study, we analysed the effect of arachidonic acid (AA) and prostaglandins (PGs) on maturation, activation and pronuclear formation in R. arenarum oocytes. Our results demonstrated that AA was capable of inducing maturation in time-dependent and dose-dependent manner. Arachidonic acid-induced maturation was inhibited by indomethacin. PGs from AA hydrolysis, such as prostaglandin F2α (PGF2α) and, to a lesser extent, PGE2, induced meiosis resumption. Oocyte maturation in response to PGF2α was similar to that produced by progesterone (P4). Oocyte response to PGE1 was scarce. Rhinella arenarum oocyte PGF2α-induced maturation showed seasonal variation. From February to June, oocytes presented low sensitivity to PGF2α. In following periods, this response increased until a maximum was reached during October to January, a close temporal correlation with oocyte response to P4 being observed. The effect of PGF2α on maturation was verified by analysing the capacity of oocytes to activate and form pronuclei after being injected with homologous sperm. The cytological analysis of activated oocytes demonstrated the absence of cortical granules in oocytes, suggesting that PGF2α induces germinal vesicle breakdown (GVBD) and meiosis resumption up to metaphase II. In turn, oocytes matured by the action of PGF2α were able to form pronuclei after fertilization in a similar way to oocyte maturated by P4. In microinjection of mature cytoplasm experiments, the transformation of pre-maturation promoting factor (pre-MPF) to MPF was observed when oocytes were treated with PGF2α. In summary, our results illustrated the participation of the AA cascade and its metabolites in maturation, activation and pronuclei formation in R. arenarum.

Emerging organic contaminants have been monitored in stream waters, raw and finished waters and wastewater effluents. Most of these contaminants, such as epigenetic substances, have been detected at very low levels. Unfortunately, their complete monitoring and/or removal are very difficult, given the increasing presence of new contaminants and due to analytical and economic considerations. For this reason, bioindicators are used as an alternative to monitor their presence. To this end, zebrafish is being used to assess certain contaminants in water quality studies.

As our long-term aim is to determine if zebrafish (Danio rerio) can be used to detect environmental epigenetic factors in drinking waters with effects on human reproduction, an initial question is whether the chorion could interfere with the possible action of epigenetic factors in two reproductive events: genital ridge formation and migration of the primordial germ cells (PGCs) to these genital ridges.

In the first experiment, we attempted to partially degrade the chorion of mid blastula transition (MBT) embryos with pronase, with acceptable survival rates at 5 days post fertilisation (dpf), with the group exposed for 15 min giving the best survival results. As denuded early embryos require a specific culture medium, in the next experiment embryo survival was evaluated when they were cultured up to 5 dpf in drinking waters from six different sources. Results showed a negative effect on embryo survival at 5 dpf from several waters but not in others, thus distorting the survival outcomes. These results suggest using embryos with the chorion intact from the outset when drinking waters from different sources are to be tested.

In vitro fertilization (IVF) can be used to assess the fertilization capacity of sperm. Heterologous IVF may be useful when assessing that of wild animals as it is often difficult to obtain adequate numbers of naturally corresponding oocytes. The aim of the present study was to assess the fertilization capacity of frozen–thawed ibex epididymal spermatozoa via heterologous IVF involving the oocytes of prepubertal domestic goats. The effect on fertilization and embryo development of adding oestrous sheep serum (ESS) to the fertilization medium was also examined. Cumulus–oocyte complexes (COCs) were matured in TCM-199 for 24–27 h at 38.5°C in a 5% CO2 in air atmosphere. Frozen–thawed epididymal spermatozoa were selected by density gradient centrifugation. After maturation, the oocytes were co-incubated with spermatozoa in synthetic oviductal fluid (SOF) with different concentrations of ESS: SOF-C (0%), SOF-2 (2%) and SOF-20 (20%). At 17 h post-insemination (hpi), zygotes with one female and one male pronucleus (2PN) were categorised as normal; zygotes with 3PN were recorded as polyspermic, and oocytes with 1PN as asynchronous. Cleavage and blastocyst development were assessed at 48 and 168 hpi respectively. The percentage of zygotes with 2PN was higher in the SOF-2 than in the SOF-20 treatment group (27.7% versus 2.9% P < 0.05). The percentage of blastocysts formed with the SOF-C, SOF-2 and SOF-20 treatments were 1.1%, 7.5% and 0% respectively. These results show that the presence of 2% ESS achieves better results than the use of no serum or the standard 20% concentration. Heterologous IVF may be an effective method for predicting the fertilization capacity of ibex spermatozoa, and therefore perhaps that of other wild mountain ungulates.

Previous studies have reported that the first polar body (PB1) morphology reflects embryo development competence, but the effects of PB1 on porcine embryo development remain unknown. This study aims to determine whether the ability of porcine embryo development is related to oocytes’ PB1 in vitro. The distribution of type II cortical granules (CGs) of porcine matured oocytes in grade B PB1 is significantly greater compared with those in grades A and C PB1 (71.43% versus 52.46% and 50%; P < 0.05). The ratio of porcine parthenogenetic blastocysts and the mean cell number in each blastocyst in the group with grade B PB1 is significantly greater than that with grades A and C PB1 (30.81% vs. 19.02% and 15.15%; P < 0.05) and (36.67 versus 24.67, 28.67; P < 0.05), and no significant differences are found in the embryo cleavage for all groups (79.75%, 84.30%, and 78.18% in grades A, B, and C PB1; P > 0.05). The acetylation level of porcine embryos in the group with grade B PB1 is significantly greater compared with those in the other groups (P < 0.05), and is almost 2.5 times higher than that in grade A. Therefore, porcine oocytes with PB1 in grade B are more competitive in cytoplasmic maturation and further embryo development in vitro.

Cryopreservation has not been used successfully to preserve fish embryos, although chilling techniques have been used with good results. The aim of this study was to chill Piaractus brachypomus embryos at – 10°C for various storage times. Embryos at the following ontogenetic stages were used: blastoderm – 1.2 hours post-fertilization (hpf); epiboly – 5 hpf; blastopore closure – 8 hpf; and appearance of the optic vesicle – 13 hpf. One hundred embryos were selected from each ontogenetic stage and chilled at – 10°C for 6 or 10 h. The results were analysed using analysis of variance (ANOVA) and Tukey's test at a 5% significance level. A significantly greater number of completely developed live larvae were observed following embryonic treatment with a cryoprotectant solution that contained 17.5% sucrose and 10% methanol. There was no survival for embryos cooled at – 10°C in initial developmental stages (1, 2 and 5 h hpf). Furthermore, higher survival rates were observed when embryos were treated at more advanced developmental stages (8 and 13 hpf). Therefore, P. brachypomus embryos at the blastopore-closure (8 hpf) or appearance-of-optic-vesicle (13 hpf) stages should be used for embryo chilling protocols and chilling should be performed using a 17.5% sucrose with a 10% methanol solution at – 10°C for up to 6 h. The best results were obtained with 13-hpf and 8-hpf embryos and cooling at 6 h of storage.

The aim of this study was to evaluate the effect of the addition of Ficoll 70 into the cryopreservation medium containing sucrose and dimethyl sulfoxide (DMSO) on rabbit spermatozoa characteristics following freezing/thawing. This large molecular weight polymer elevates the viscosity of medium and, therefore, could better protect spermatozoa during the freezing process. Only ejaculates of good initial motility (>80%) were used in the experiments. Heterospermic pools were diluted in a freezing medium composed of commercial diluent, 16% dimethyl sulphoxide (DMSO) and 2% sucrose (control) or in the same medium enriched with 4% Ficoll 70 (Ficoll) and frozen in liquid nitrogen vapours for 10 min before being plunged in liquid nitrogen. The quality of fresh and frozen/thawed spermatozoa samples was evaluated in vitro using the Computer Assisted Semen Analysis (CASA) system, fluorescent probes (peanut agglutinin (PNA)-Alexa Fluor®; annexin V-FLOUS) and by electron microscopy. Better cryoprotective effect was observed when Ficoll 70 was added, compared with the semen cryopreserved with sucrose and DMSO only. The higher values (P < 0.05) of motile and progressively moving spermatozoa immediately after thawing and at 30 min following incubation at 37°C were obtained in the Ficoll group. Moreover, the higher number (P < 0.05) of acrosome intact sperm was found in the Ficoll compared with the control group. Furthermore, no significant differences in kindling rates and number of pups born between frozen/thawed and fresh semen group were found. In conclusion, our study showed that the addition of Ficoll 70 might improve several characteristics of rabbit spermatozoa measured in vitro following freezing/thawing.

Immature bovine oocytes were vitrified using the cryotop method and their post-warming survivability and capability to undergo in vitro maturation, fertilization and subsequent embryonic development were evaluated. In addition throughout the embryonic 2-cell, 4-cell, morula and blastocyst stages, the expression of four developmentally important genes (Cx43, CDH1, DNMT1 and HSPA14) was analysed using the real-time polymerase chain reaction (PCR). Immature oocytes (n = 550) were randomly assigned to non-vitrified (fresh) or cryotop vitrification groups using ethylene glycol (EG) with 1,2 propanediol (PROH) or dimethylsulphoxide (DMSO). After warming, oocytes survivability, embryo cleavage and embryonic developmental rates were not statistically different between the two cryoprotectants groups. However, the DMSO group had a lower (P < 0.05) oocyte maturation rate compared with the fresh and PROH groups. For morula and blastocyst rates, the DMSO group achieved a lower (P < 0.05) morula rate compared with the fresh group, while at the blastocyst stage, there were no differences between fresh and both cryoprotectants groups. For molecular analysis, at the 4-cell stage, most studied genes showed an inconsistent pattern of expression either from the PROH or DMSO groups. Noteworthily, these differences were limited at the morula and blastocyst stages. In conclusion, the cryotop method is sufficient for vitrification of immature bovine oocytes, both for embryonic developmental competence and at the molecular level. Moreover, PROH showed some advantage over DMSO as a cryoprotectant.

Growth hormone (GH) plays an important role in early embryo development. It has been shown to activate multiple pathways, the most comprehensively studied being the STAT/JAK (Signal transducers and activators of transcription/Janus kinase) pathway. The objective of the present study was to investigate STAT5A gene expression during early bovine embryogenesis. Real-time polymerase chain reaction (RT-PCR) was used to measure the abundance of STAT5A transcripts. The mRNA was present at all stages of preimplantation bovine embryos investigated. The most abundant STAT5A expression occurred at the 2-cell stage. Expression was markedly reduced between the 4-cell and 8-cell stages, coinciding with the known time of embryo genome activation and loss of maternal mRNAs. This finding suggests that the embryonic STAT5A gene is primarily activated by maternal gene products.

The topic of monozygotic twinning (MT) on which the recent paper by Herranz (Herranz, 2013) focuses is indeed a fascinating one, not only for the embryologist. And, as pointed out by the author, it may on principle also be relevant for ethical discussions in the context of embryo research and stem cell work in humans. Obviously, this is the reason why the paper was published in Zygote, in spite of the fact that it concentrates on history and speculation. When reading through the paper, however, I have ended up disappointed.

The aim of this study was to investigate the effect of ovarian tissue transportation conditions (medium and period of time) on the morphology, apoptosis and development of ovine preantral follicles cultured in vitro. Each ovarian pair was cut into nine slices, with one fragment being fixed immediately (fresh control). The remaining fragments were placed individually in cryotubes containing conservation medium (minimal essential medium (MEM) without supplementation or MEM+ – with supplementation) and stored at 35ºC for 6 or 12 h without (non-cultured) or with subsequent culture for 5 days. Then, the fragments were processed for histological and terminal deoxynucleotidyl transferase (TdT) mediated dUTP nick-end labelling (TUNEL) examination. Preservation of ovarian slices in MEM or MEM+ (non-cultured) resulted in similar percentages of normal follicles when compared with the fresh control. Nevertheless, compared with the fresh control, a decrease in the percentage of normal follicles was observed in tissues cultured for 5 days. Only for tissues preserved in supplemented medium (MEM+) for 6 h, the percentage of TUNEL positive cells was similar between non-cultured tissues and tissues cultured for 5 days. Follicular activation and growth (follicular and oocyte diameter) were higher in cultured tissues than in fresh control or non-cultured tissues, except those from fragments preserved for 6 h in MEM and then cultured for 5 days in which no growth was observed. In conclusion, ovine ovarian tissue was successfully preserved in supplemented medium (MEM+) at a temperature close to physiological values (35°C) for up to 6 h without affecting apoptosis in the ovarian follicles and their ability to develop in vitro.

Osteopontin (OPN) is a multifunctional phosphoprotein that is detected in various tissues, including male and female reproductive tracts. In this study, we evaluated OPN expression in mouse oviducts during the estrus cycle, and at days 1–5 of pregnancy and pseudopregnancy by reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry. The mice oocytes, sperm and embryos were treated with different concentrations of anti-OPN antibody in vitro to detect the function of OPN in fertilization and preimplantation embryo development. OPN mRNA and protein expression in mouse oviducts were cyclic dependent throughout the estrous cycle, which was highest at estrous and lowest at diestrous. Such a phenomenon was consistent with the change in estrogen level in mice. The expression levels of OPN in mice oviduct of normal pregnancy and pseudopregnancy were significantly different, which indicated that OPN expression in mouse oviducts was depend on estrogen and preimplantation embryo. Furthermore, anti-OPN antibody treatment could reduce the rates of fertilization, cleavage and blastocyst formation in vitro in a dose-dependent way. Overall, our results indicated that the expression of OPN in mouse oviducts during the estrous cycle and early pregnancy is likely regulated by estrogen and the embryo, and OPN may play a vital role in oocyte fertilization and preimplantation embryo development.