Transvaginal Ultrasound-guided Follicle Aspiration Research Articles

Use of excised ovaries for oocyte recovery by ultrasound guided follicular aspiration – Validation of an experimental model for research purposes in live mares ovum pick up

Ovum pick-up (OPU) by transvaginal ultrasound guided follicle aspiration in mares is a common assisted reproductive technique used for oocyte recovery and in vitro production of horse embryos. There has been relatively little research into the factors influencing oocyte recovery in OPU from live mares. The objective of this study was to compare oocyte recovery and morphology of ultrasound-guided follicle puncture and aspiration in live mares and in postmortem excised ovaries, in order to validate an experimental model for research purposes of the efficiency of OPU in mares. Data from OPU performed in 12 mares from a commercial program (follicle numbers, oocyte recovery and oocyte morphology) were compared to that obtained from ultrasound-guided follicle puncture of 13 postmortem excised ovaries from slaughtered mares processed within 2 h of slaughter. In both groups, the OPU was performed by the same operator using the same equipment and OPU technique. The recovered oocytes per aspirated follicle was higher (P < 0.05) in the postmortem group (105/166, 63.2 %) than in live mares (138/261, 52.9 %). There was more (P < 0.05) expanded cumulus oocyte complexes in the postmortem than in the live mares (18 % vs. 2.9 %). Several oocytes (5 oocytes from 81 aspirated follicles) were found in the leaked fluid which overflowed during follicle flushing of postmortem ovaries. In conclusion, the higher recovery rate obtained in the excised ovaries and the finding of oocytes in the leaked fluid during OPU, suggests that there is still room for improvement in the in vivo OPU technique. Utilizing postmortem excised ovaries could offer an alternative for further research into factors affecting oocyte recovery and oocyte leakage during OPU procedures.

Transvaginal aspiration, oocyte maturation and production of blastocysts and a pregnancy via ICSI in an endangered breed: Baudet du Poitou donkey

Two Poitou donkey jennies were presented for clinical oocyte recovery and embryo production via intracytoplasmic sperm injection (ICSI). Both jennies underwent transvaginal ultrasound-guided follicle aspiration on two occasions. Recovered oocytes were held overnight then placed into maturation culture, using standard methods for mare oocytes. On the first replicate for both jennies, the oocytes were divided into two groups; one group was denuded and examined at 30 h culture (standard culture duration for mare oocytes) and the second was denuded and examined at 36 h culture. No oocytes with polar bodies were observed at either time. The oocytes were maintained in maturation culture until 46 h, at which time oocytes with polar bodies were observed. Semen was then prepared; oocytes underwent ICSI approximately 48 h after being placed into maturation culture. On the second replicate for both jennies, oocytes were cultured for maturation for 42 h, then denuded and subjected to ICSI at 46 h. Sperm preparation, injection and embryo culture were performed as for mare oocytes. Blastocyst rates per injected oocyte were 8/19 (42 %) overall, being 4/12 and 4/7 for the first and second TVAs, respectively. Blastocysts were vitrified. Three blastocysts were warmed and transferred to Poitou donkey jenny recipients. One embryonic vesicle was visualized on ultrasonography on embryo Day 12, which increased in size on Day 13 but was not present when examined on Day 14. These results demonstrate that oocyte recovery and ICSI are efficient for production of Poitou donkey blastocysts. To the best of our knowledge, this is the first report of production of blastocysts via ICSI in the Poitou donkey, and the first report of transfer of ICSI-produced embryos in the donkey. Further work is needed on factors affecting pregnancy after embryo transfer in the donkey.

Evaluation of the effects of the recommended oral dose of diflubenzuron on bovine sperm and oocyte quality using CASA and OPU-IVEP.

The aim of this study was to evaluate potential effects of diflubenzuron on the production and quality of gametes, and on in vitro embryo production (IVEP) outcomes, in cattle. Two experiments were performed, the first to evaluate effects on semen, and the second on cumulus-oocyte complexes (COC) and on IVEP. Nelore (Bos taurus indicus) bulls (n = 14) or heifers (n = 16) were allocated into control (CG) or treatment (DIF) groups. All groups received a mineral mix supplement added (DIF) or not (CG) with diflubenzuron (30 mg/head/day), during 8 weeks. Animals were weighed and blood samples were collected throughout the experimental period. Every other week, bulls were subjected to semen collection and heifers to transvaginal ultrasound-guided follicle aspiration sessions. Semen underwent physical and morphological evaluation, and samples were stored for further computer-assisted sperm analysis. The COC recovered were evaluated according to morphology and those classified as viable were sent to an IVEP laboratory. Diflubenzuron had no effect (P > 0.05) on average body weight or in any blood hematological or biochemical endpoints, regardless of gender. In experiment 1, there was no difference (P > 0.05) between DIF and CG groups for sperm concentration, morphology, or kinetics. In experiment 2, there was also no effect of diflubenzuron on the number of total, viable, or grade I oocytes, as well as on cleavage or blastocyst rates (P > 0.05). In summary, the oral administration of diflubenzuron, within the recommended dose, has no short-term negative effects on sperm production and quality or on oocyte yield and developmental potential in vitro, in cattle.

Blastocyst production using a new equine FSH for in vitro maturation

Currently, the majority of the equine ART laboratories collect germinal vesicle (GV)-stage oocytes to perform ICSI, and the gonadotrophins used for in vitro maturation are mainly porcine, bovine, or human. In this study, the effect of two different concentrations of equine FSH (eFSH) in the maturation medium was evaluated. Cumulus-oocytes complexes (COCs) were collected via ultrasound-guided transvaginal follicle aspiration and randomly allotted to the groups. The control group was our standard maturation medium (BMM - TCM199-Earle's salts, 10% FBS, and additives) with human gonadotrophins added (Lazzari.et.al. Journal of Equine Veterinary Science. 2020; 89:103097); experimental groups were composed of BMM with eFSH added (0.01 and 0.05 IU/mL). After holding, COCs were transferred to maturation medium and cultured for 36h. ICSI was performed, and presumptive zygotes were cultured. The cleavage rate and number of cells were evaluated on D3, blastocyst formation and embryo quality, classified on A-B-C grade scale (adapted from Lewis.et.al. Reproduction, Fertility and Development. 2023; 35: 338-351), were evaluated from D6-10. Differences were analyzed by Fisher's Exact Test (significance level P<0.05). There was no difference (P>0.05) in degenerated, GV-stage, or MI oocytes after maturation for control, 0.01, and 0.05, respectively. The number of oocytes that reached the (meiosis) MII-stage was lower (P<0.05) for 0.01 U/mL (56.5%, 35/62)than the control (73.2%, 52/71), and also tended to be lower (P=0.0985) compared to 0.05 U/mL (71.2%, 47/66). There was no difference in cleavage or cell number among groups (Table 1). Group 0.01 U/mL had a higher (P<0.05) blastocyst rate (45.7%, 16/35) than control and 0.05 U/mL groups (28.8%,15/52; 25.5%, 12/47; respectively). No difference was found in embryo quality among groups. Although the 0.01 U/mL group showed a lower MII rate, it also showed numerically less 2-cell stage embryos, more 4-8 and 8-16 cells stage embryos, and more cleaved embryos. Additionally, the 0.01 U/mL group tended to have more high-quality embryos (grade A) than the control group and showed a higher total blastocyst rate compared to the other groups. Additional studies are required to establish an ideal maturation protocol using this new equine FSH.

203 Effect of aspiration pressure at the time of transvaginal ultrasound-guided follicle aspiration on cumulus-oocyte complex quality and embryo development in alpacas (

Reproduction, Fertility and Development is an international journal publishing original research , review and comment in the fields of reproduction and developmental biology in humans, domestic animals and wildlife

Effect of day of estrus cycle at time of transvaginal follicle aspiration for oocyte recovery on rates of in vitro maturation and blastocyst production after intracytoplasmic sperm injection.

To determine the effect of stage of estrus cycle (day after ovulation) at the time of transvaginal ultrasound-guided follicle aspiration (TVA) on parameters related to the success of in vitro equine embryo production. 14 healthy mares were used; 11 completed the study and were included for analysis. Mares underwent TVA of all follicles ≥ 5 mm diameter at each of 3 timepoints: 7 days after ovulation, 14 days after ovulation, and S-DSF (subordinate to a dominant stimulated follicle), during estrus at 24 hours after gonadotropin administration. The 3 treatments were assigned to each mare in random order; mares underwent follicle growth and ovulation between treatments. Recovered oocytes were matured in vitro, subjected to intracytoplasmic sperm injection (ICSI), and cultured to the blastocyst stage in vitro. Total follicle numbers differed significantly between individual mares but did not differ between treatments. The number of follicles of different sizes significantly (P < 0.05) differed between treatments, with mares in the Day 7 treatment having more follicles 5 to 9 mm in diameter and fewer follicles 20 to 24 mm in diameter than mares in the other 2 treatments. After in vitro maturation culture, there were significantly more mature oocytes in the S-DSF treatment than in the other 2 treatments. There were no differences in blastocyst rate after ICSI among treatment groups. Timing of TVA for aspiration of S-DSFs may increase the number of mature oocytes available for ICSI. Understanding of the effects of timing of TVA will help veterinarians to maximize the efficiency of this procedure.

Comparative study between general anesthesia and conscious sedation for oocyte retrieval on hemodynamic recovery and oocyte quality

Background: In vitro fertilization (IVF) is a four-stage procedure, ovarian stimulation and monitoring, oocyte retrieval, fertilization and embryo transfer. Transvaginal ultrasound–guided follicle aspiration is the most common method for oocyte retrieval in assisted reproductive technologies, it is increasingly performed as an outside procedure. Objective: To compare between general Anesthesia and Conscious Sedation according to Oocyte Retrieval on hemodynamic recovery and oocyte quality. Methods: Seventy women underwent oocyte retrieval in the period from November 2021 till June 2022 at High Institute of Infertility Diagnosis and Assisted Reproductive Technique, Reproductive Physiology, Al-Nahrain University in Baghdad, Iraq, were included in this study. Results: Mean time needed for operation was 9.06± 1.39 minutes in conscious group and 9.84± 1.11 minutes in GA group, and the recovery time needed was 2.31± 0.47 hours in conscious group and 10.78± 1.87hours in GA group. Conclusion: Significant decrease in duration of operation in conscious group than that in general anesthesia group (P=0.01), moreover, highly significant decrease in recovery time in conscious group than that in GA group (P&lt;0.001)

In vitro production of ICSI derived horse blastocysts

In vitro production of horse embryos via intracytoplasmic sperm injection (ICSI) is a useful clinical and research technique. However, current rates of blastocyst production are still sub-optimal. Here, we compared results from our commercial ICSI program to evaluate whether slight modifications in protocols can result in improved blastocyst rates. Firstly, we evaluated the time cumulus oocyte complexes (COCs) can be maintained in holding medium before starting in vitro maturation (IVM) (Group A: 4-10 hours and Group B: overnight). Secondly, we evaluated the effects of using a microfluidic device (Zymöt) for the preparation of sperm samples for ICSI (Group C). This device comprises a microporous membrane that allows to select spermatozoa in base of their motility, avoiding samples centrifugation. This could eventually reduce DNA fragmentation and oxidative stress, which have been associated with conventional sperm preparation protocols. Frozen-thawed cut straws with semen from different stallions were used and prepared either with a gradient and swim-up protocol or with the Zymöt microfluidic device. COCs were recovered from immature follicles using transvaginal ultrasound-guided follicle aspiration (TVA) procedures. After collection, COCs were transferred to holding medium for 4 to 10 hours or maintained in holding medium overnight at room temperature (22–24°C) before starting IVM. In vitro maturation was performed in T-199 Earle's medium supplemented with 5 mU/ml FSH, 50 ng/ml EGF and 10% FBS. After IVM, oocytes were denuded from cumulus and those showing a polar body were subjected to piezo-ICSI (PiezoXpert, Eppendorf). Spermatozoa were first immobilized with strong piezo pulses and then injected individually in the matured oocytes after penetrating the zona pellucida and oolemma with low intensity pulses.The injected oocytes were then cultured in a mix of KSOM-DMEM/F12 medium supplemented with 6% FBS, which was refreshed on Day 5 of development. Embryo culture was performed in humidified benchtop incubators at 6.5% CO2 and 5%O2 at 38.2°C. A Chi-square test was used to compare results.

β-NGF Stimulates Steroidogenic Enzyme and VEGFA Gene Expression, and Progesterone Secretion via ERK 1/2 Pathway in Primary Culture of Llama Granulosa Cells.

The beta-nerve growth factor (β-NGF) from llama seminal plasma exerts ovulatory and luteotrophic effects following intramuscular or intrauterine infusion in llamas and alpacas. In this study, we investigate the in vitro effect of llama β-NGF on the expression of genes involved in angiogenesis and progesterone synthesis as well as progesterone release in preovulatory llama granulosa cells; we also determine whether these changes are mediated via the ERK1/2 signaling pathway. From adult female llamas, we collected granulosa cells from preovulatory follicles by transvaginal ultrasound-guided follicle aspiration; these cells were pooled and incubated. After 80% confluence, the cultured granulosa cells were treated with β-NGF, β-NGF plus the MAPK inhibitor U0126, or luteinizing hormone, and the abundance of angiogenic and steroidogenic enzyme mRNA transcripts were quantified after 10 and 20 h by RT-qPCR. We also quantified the progesterone concentration in the media after 48 h by radioimmunoassay. We found that application of β-NGF increases the abundance of mRNA transcripts of the vascular endothelial growth factor (VEGFA) and the steroidogenic enzymes cytochrome P450 side-chain cleavage (P450scc/CYP11A1), steroidogenic acute regulatory protein (STAR), and 3β-hydroxysteroid dehydrogenase (HSD3B1) at 10 and 20 h of treatment. Application of the MAPK inhibitor U0126 resulted in downregulation of the genes encoding these enzymes. β-NGF also enhanced progesterone synthesis, which was prevented by the prior application of the MAPK inhibitor U0126. Finally, western blot analysis confirmed that β-NGF activates the ERK1/2 signaling pathway. In conclusion, our results indicate that β-NGF exerts direct luteotropic effects on llama ovarian tissue via the ERK 1/2 pathway.

Two waves of transcriptomic changes in periovulatory human granulosa cells.

How does the human granulosa cell (GC) transcriptome change during ovulation? Two transcriptional peaks were observed at 12h and at 36h after induction of ovulation, both dominated by genes and pathways known from the inflammatory system. The crosstalk between GCs and the oocyte, which is essential for ovulation and oocyte maturation, can be assessed through transcriptomic profiling of GCs. Detailed transcriptional changes during ovulation have not previously been assessed in humans. This prospective cohort study comprised 50 women undergoing fertility treatment in a standard antagonist protocol at a university hospital-affiliated fertility clinic in 2016-2018. From each woman, one sample of GCs was collected by transvaginal ultrasound-guided follicle aspiration either before or 12h, 17h or 32h after ovulation induction (OI). A second sample was collected at oocyte retrieval, 36h after OI. Total RNA was isolated from GCs and analyzed by microarray. Gene expression differences between the five time points were assessed by ANOVA with a random factor accounting for the pairing of samples, and seven clusters of protein-coding genes representing distinct expression profiles were identified. These were used as input for subsequent bioinformatic analyses to identify enriched pathways and suggest upstream regulators. Subsets of genes were assessed to explore specific ovulatory functions. We identified 13 345 differentially expressed transcripts across the five time points (false discovery rate, <0.01) of which 58% were protein-coding genes. Two clusters of mainly downregulated genes represented cell cycle pathways and DNA repair. Upregulated genes showed one peak at 12h that resembled the initiation of an inflammatory response, and one peak at 36h that resembled the effector functions of inflammation such as vasodilation, angiogenesis, coagulation, chemotaxis and tissue remodelling. Genes involved in cell-matrix interactions as a part of cytoskeletal rearrangement and cell motility were also upregulated at 36h. Predicted activated upstream regulators of ovulation included FSH, LH, transforming growth factor B1, tumour necrosis factor, nuclear factor kappa-light-chain-enhancer of activated B cells, coagulation factor 2, fibroblast growth factor 2, interleukin 1 and cortisol, among others. The results confirmed early regulation of several previously described factors in a cascade inducing meiotic resumption and suggested new factors involved in cumulus expansion and follicle rupture through co-regulation with previously described factors. The microarray data were deposited to the Gene Expression Omnibus (www.ncbi.nlm.nih.gov/gds/, accession number: GSE133868). The study included women undergoing ovarian stimulation and the findings may therefore differ from a natural cycle. However, the results confirm significant regulation of many well-established ovulatory genes from a series of previous studies such as amphiregulin, epiregulin, tumour necrosis factor alfa induced protein 6, tissue inhibitor of metallopeptidases 1 and plasminogen activator inhibitor 1, which support the relevance of the results. The study increases our understanding of human ovarian function during ovulation, and the publicly available dataset is a valuable resource for future investigations. Suggested upstream regulators and highly differentially expressed genes may be potential pharmaceutical targets in fertility treatment and gynaecology. The study was funded by EU Interreg ÔKS V through ReproUnion (www.reprounion.eu) and by a grant from the Region Zealand Research Foundation. None of the authors have any conflicts of interest to declare.

Resistant Ovary Syndrome Masquerading as Premature Ovarian Insufficiency

Premature ovarian insufficiency (POI) is typically the end result of premature depletion of primordial follicles. However gonadotropin-resistant ovary syndrome could result in a similar clinical and laboratory picture with a more favorable outcome. A 29-year-old G0 woman with POI referred to our infertility clinic for egg donation. On ultrasound, her ovaries contained multiple resting antral follicles (AFs). Patient underwent transvaginal ultrasound-guided follicle aspiration of all visible small antral follicles. Eggs were in vitro matured and resulting embryos cryopreserved. Patient achieved a successful live birth with her own eggs. Gonadotropin-resistant ovary syndrome must be considered in all women diagnosed with hypergonadotropic hypogonadal POI and normal antral follicle count (AFC) and anti-Mullerian hormone (AMH). In these patients, pregnancy can be achieved with their own eggs. J Clin Gynecol Obstet. 2019;8(4):111-113 doi: https://doi.org/10.14740/jcgo575

The effect of seminal plasma \u03b2-NGF on follicular fluid hormone concentration and gene expression of steroidogenic enzymes in llama granulosa cells

BackgroundNerve growth factor (β-NGF) from llama seminal plasma has been described as a potent ovulatory and luteotrophic molecule after intramuscular or intrauterine infusion in llamas and alpacas. We tested the hypothesis that systemic administration of purified β-Nerve Growth Factor (β-NGF) during the preovulatory stage will up-regulate steroidogenic enzymes and Vascular Endothelial Growth Factor (VEGF) gene expression in granulosa cells inducing a change in the progesterone/estradiol ratio in the follicular fluid in llamas.MethodsExperiment I: Female llamas (n = 64) were randomly assigned to receive an intramuscular administration of: a) 50 μg gonadorelin acetate (GnRH, Ovalyse, Pfizer Chile SA, Santiago, Chile, n = 16), b) 1.0 mg of purified llama β-NGF (n = 16), or c) 1 ml phosphate buffered saline (PBS, negative control group, n = 16). An additional group of llamas (n = 16) were mated with a fertile male. Follicular fluid and granulosa cells were collected from the preovulatory follicle at 10 or 20 h after treatment (Time 0 = administration of treatment, n = 8/treatment/time point) to determine progesterone/estradiol concentration and steroidogenic enzymes and VEGF gene expression at both time points. Experiment II: Granulosa cells were collected from preovulatory follicles from llamas (n = 24) using ultrasound-guided transvaginal follicle aspiration for in vitro culture to determine mRNA relative expression of Steroidogenic Acute Regulatory Protein (StAR) and VEGF at 10 or 20 h (n = 4 replicates) and progesterone secretion at 48 h (n = 4 replicates) after LH or β-NGF treatment.ResultsExperiment I: There was a significant increase in the progesterone/estradiol ratio in mated llamas or treated with GnRH or purified β-NGF. There was a significant downregulation in the mRNA expression of Aromatase (CYP19A1/P450 Arom) for both time points in llamas mated or treated with GnRH or llama purified β-NGF with respect to the control group. All treatments except β-NGF (20 h) significantly up regulated the mRNA expression of 3-beta-hydroxysteroid dehydrogenase (HSD3B) whereas the expression of StAR and Side-Chain cleavage enzyme (CYP11A1/P450scc) where significantly up regulated only by mating (20 h), or β-NGF at 10 or 20 h after treatment. VEGF was up regulated only in those llamas submitted to mating (10 h) or treated with purified β-NGF (10 and 20 h). Experiment II: Only β-NGF treatment induced an increase of mRNA abundance of StAR from llama granulosa cells at 20 h of in vitro culture. There was a significant increase on mRNA abundance of VEGF at 10 and 20 h of in vitro culture from granulosa cells treated with β-NGF whereas LH treatment increases VEGF mRNA abundance only at 20 h of in vitro culture. In addition, there was a significant increase on progesterone secretion from llama granulosa cells 48 h after LH or β-NGF treatment.ConclusionsSystemic administration of purified β-NGF from llama seminal fluid induced a rapid shift from estradiol to progesterone production in the preovulatory follicle. Differences in gene expression patterns of steroidogenic enzymes between GnRH and mated or β-NGF-treated llamas suggest local effects of seminal components on the preovulatory follicle.

133 In Vitro Embryo Production from Oocytes Collected from Non-Supertimulated Wood Bison (Bison bison athabascae) Following Maturation In Vitro Using Portable Incubators

This study was done to determine the feasibility of in vitro embryo production in wood bison during the anovulatory season, without ovarian superstimulation or follicle wave synchronization, to simulate collection conditions in a wild or field setting. The experiment provided the opportunity to compare embryo development using 2 different maturation media and incubator systems. The cumulus-oocyte complexes (COC) were collected by transvaginal ultrasound-guided follicle aspiration during May from non-superstimulated bison. Compact COC were allocated to 2 groups and matured in standard maturation medium using a portable gassed incubator, or in commercial medium using a portable non-gassed incubator. In the former (Standard), the COC were placed in a round-bottomed tube containing TCM-199 medium with 5% calf serum, 5 μg mL−1 LH, 0.5 μg mL−1 FSH, and 0.05 μg mL−1 gentamicin, and the tube was placed in a portable incubator with 5% CO2. In the latter (Commercial), COC were placed in a round-bottom tube containing the commercial medium (Boviteq, Saint-Hyacinthe, QC, Canada), and placed in a portable incubator without CO2. After 24 h of maturation, oocytes were fertilized in vitro (Day 0) in Brackett-Oliphant medium at 38.5°C in a conventional incubator with 5% CO2 humidified atmosphere. Presumptive zygotes were cultured in CR1aa plus 5% calf serum, at 38.5°C and in 5% CO2, 5% O2, and 90% N2 and high humidity. Cleavage was recorded on Day 3 and embryo development was recorded on Day 7. Cleavage and transferable embryo rates (calculated from the total number of oocytes submitted to IVF) were compared between groups by chi-squared test. No difference in cleavage rates was observed between Standard and Commercial treatment groups [68.1 (32/47) v. 79.2% (57/72), respectively; P = 0.25], nor in morula plus blastocyst rates on Day 7 (36.2 v. 45.8%, respectively; P = 0.39). However, the rate of transferable embryos (grade 1 and grade 2) on Day 7 was higher in the Commercial group (38.9 v. 12.8%; P &lt; 0.01). Of the COC in the Commercial group, a higher number of morula plus blastocyst were observed to be compact good COC (&gt;3 layers of cumulus cells) than compact regular COC (1-3 layers of cumulus cells) (66.7 v. 31.0% respectively; P &lt; 0.05), along with a higher number of transferable embryos on Day 7 (60.0 v. 23.8%, respectively; P &lt; 0.05). In conclusion, wood bison oocytes collected during the anovulatory season from non-superstimulated, non-synchronized bison and matured in vitro using portable incubators were competent to develop to the morula and blastocyst stages following IVF and culture. These results are important for future plans that require transporting oocytes from remote collection sites to the IVF laboratory, particularly with respect to the effectiveness of commercial maturation media which does not require CO2 supplementation. Research was supported by the Natural Sciences and Engineering Research Council of Canada.

Characterization of blood flow and the effects of exogenous estradiol benzoate on residual follicles formed after ultrasound-guided transvaginal follicle aspiration in cattle.

BackgroundRemoval of the follicular content by ultrasound-guided transvaginal follicle aspiration (TVFA) may fail to induce immediate atresia and loss of function, resulting in the occurrence of residual follicles (RF). The aims of this study were to characterize the blood flow in RF and to determine the effects of the treatment with estradiol benzoate on RF fate. Lactating, cyclic Holstein-Gir crossbred cows were used. In Experiment 1, follicular wave emergence (D0) was synchronized in cows (n = 10) and follicular growth was then monitored by transrectal ultrasonography from D0 to D8, followed by TVFA of the largest follicle present on the ovaries 24 h later. Color Doppler ultrasound imaging was used to examine blood flow on the follicular wall, which was recorded immediately before and every 12 h after TVFA, up to 72 h. In experiment 2, cows (n = 22) were randomly allocated to receive either 2 mL of saline i.m. (Control group, n = 11) or 2 mL estradiol benzoate i.m. (EB group, n = 11) immediately after TVFA. Ovaries were scanned every 12 h to confirm the presence and to measure the diameter of RF. The contents of the RF, if present, were collected 72 h after the first TVFA, using the same aspiration procedures. Follicular fluid from original follicles and RF were stored at -20 °C until hormonal assays.ResultsIn Experiment 1, there was no reduction (P > 0.05) of blood flow in the remaining follicle walls after TVFA and maximum blood flow values were observed at 49.5 ± 19.7 h post-TVFA. In Experiment 2, formation of RF after TVFA was proportionally similar between Controls (5/9) and EB (5/10) cows. Also, RF diameter did not differ between groups (P > 0.05). Nonetheless, the content of RF from cows in the EB group had lower (P = 0.0004) estradiol (E2) concentration and lower (P = 0.0005) E2:P4 ratio compared with Controls.ConclusionsIn conclusion, 1) the persistence of vascularization in the remaining follicle wall may contribute to the formation of RF after follicle aspiration, and 2) the treatment with estradiol benzoate does not prevent formation of RF, but does reduce their estradiol production.

Effect of clinically-related factors on in vitro blastocyst development after equine ICSI

Equine intracytoplasmic sperm injection (ICSI) is being used clinically for foal production, but little information is available on factors affecting the efficiency of this procedure. We examined factors that may influence blastocyst development when ICSI is performed clinically, i.e., on oocytes recovered from live mares by transvaginal ultrasound-guided follicle aspiration (TVA), using sperm from the stallion of the client's choice. In a clinical setting, there may be a delay from the time of TVA to isolation of oocytes from the aspirated fluid. In a preliminary study, oocytes from fluid held for 1.5 h at ambient temperature (26°C–33°C) yielded 32% blastocysts; however, in experiment 1, fluid held at 32 °C for 2 h after aspiration yielded 16% blastocysts versus 23% for aspirates processed immediately. Performing TVA/ICSI throughout the year would increase production from valuable mares, but efficiency during the nonbreeding season is unknown. In addition, to reduce the possibility of infection after TVA, administration of antibiotics to the mare before TVA is indicated; however, these could affect oocyte quality. In experiment 2, follicle numbers at the time of TVA were significantly higher in December to January than for the same mares during the breeding season. Oocyte recovery rates on TVA were 60% to 66% and the blastocyst rate was 18%. An equivalent blastocyst rate (18%) was achieved after administration of ampicillin and gentamicin to mares before TVA. In experiment 3, we verified that stallion differences exist in rates of cleavage after ICSI with motile sperm. In sperm from a low-performing stallion, density-gradient centrifugation followed by swim-up was associated with significantly higher rates of cleavage (45% vs. 18%) and blastocyst development (14% vs. 0%) than those for density gradient alone. In experiment 4, parthenogenetic activation with ionomycin and 6-dimethylaminopurine yielded 40% blastocysts. Frozen–thawed sperm that were immotile after nitrogen tank failure did not produce blastocysts; exogenous activation after ICSI increased cleavage rate but did not yield blastocysts. These studies provide information on factors that may affect in vitro blastocyst formation after equine ICSI as it is performed in a clinical program.

43 MASS VITRIFICATION OF GERMINAL-VESICLE STAGE EQUINE OOCYTES

Oocyte cryopreservation has the potential to preserve female genetics. In addition, equine oocytes are not readily available in some areas, and vitrification could be used to accumulate oocytes at remote locations to provide material for research. To preserve large numbers of oocytes, a method for rapid vitrification of multiple oocytes is needed. First, we determined whether immature equine oocytes could be held overnight before vitrification, and we tested the use of a mesh+capillary-action media-removal vitrification platform. Oocytes were collected via ultrasound-guided transvaginal follicle aspiration and randomly allotted to either immediate vitrification or overnight holding (24 to 27 h in 40% M199-Earle’s salts, 40% M199-Hanks’ salts, 20% fetal bovine serum, and 0.3 mM pyruvate) then vitrification. Oocytes were vitrified using different times (1 or 4 min) in vitrification solution and first warming solution: 1v1w, 1v4w, 4v1w, and 4v4w. The base solution was MH (80% M199-Hanks’ salts and 20% fetal bovine serum). Cryoprotectant concentration (vol/vol) was increased in 3 steps until reaching 7.5% dimethyl sulfoxide and 7.5% ethylene glycol. The oocytes were then held in vitrification solution (MH with 15% dimethyl sulfoxide, 15% ethylene glycol, and 0.5 M sucrose) for either 1 or 4 min, according to treatment, and 3 to 10 oocytes were transferred to a 75-μm sterile stainless steel mesh. The mesh was placed on sterile paper to absorb excess medium, then plunged in LN. The oocytes were warmed in MH solution with 1.25 M sucrose for either 1 or 4 min, then placed in 0.62 M and 0.31 M sucrose solutions for 5 min each and undetermined time in MH. After warming, oocytes were cultured for maturation (in vitro maturation) in M199-Earle’s salts, 5 mU mL–1 FSH, and 10% fetal bovine serum. After 30 to 36 h, the oocytes were denuded and stained with Hoechst 33258. Data were analysed by Fisher’s exact test. There were no significant differences (P &gt; 0.05) in rates of meiotic resumption among timing treatments (35, 24, 26, and 39% for 1v1w, 1v4w, 4v1w, and 4v4w, respectively), nor between immediately vitrified (17/55, 31%) and overnight held-vitrified groups (18/56, 32%). In the second experiment, all oocytes were held overnight. They were vitrified and warmed using only the 1v1w and 4v4w schedules, then subjected to in vitro maturation, intracytoplasmic sperm injection, and embryo culture. The MII rate of the control group (27/37, 73%) was higher (P &lt; 0.05) than that for 1v1w (12/33, 36%) or 4v4w treatments (10/35, 29%). The cleavage rate for control (25/27, 93%) was higher than that for 1v1w (5/9, 56%) but not than that for 4v4w (6/9, 67%). Blastocyst rates were 19% (5/27), 11% (1/9), and 0% (0/9) for control, 1v1w, and 4v4w, respectively (P &gt; 0.05). These results indicate that blastocysts may be produced from equine immature oocytes vitrified en masse; however, both the maturation and blastocyst production rates were relatively low. Additional studies are required to improve the efficiency of this technique. This work was supported by the Clinical Equine ICSI Program, Texas A&amp;M University.

Cloned foal derived from in vivo matured horse oocytes aspirated by the short disposable needle system.

Transvaginal ultrasound-guided follicle aspiration is one method of obtaining recipient oocytes for equine somatic cell nuclear transfer (SCNT). This study was conducted: (1) to evaluate the possibility of oocyte aspiration from pre-ovulatory follicles using a short disposable needle system (14-G) by comparing the oocyte recovery rate with that of a long double lumen needle (12-G); (2) to investigate the developmental competence of recovered oocytes after SCNT and embryo transfer. The recovery rates with the short disposable needle vs. the long needle were not significantly different (47.5% and 35.0%, respectively). Twenty-six SCNT embryos were transferred to 13 mares, and one mare delivered a live offspring at Day 342. There was a perfect identity match between the cloned foal and the cell donor after analysis of microsatellite DNA, and the mitochondrial DNA of the cloned foal was identical with that of the oocyte donor. These results demonstrated that the short disposable needle system can be used to recover oocytes to use as cytoplasts for SCNT, in the production of cloned foals and for other applications in equine embryology

248 IN VITRO EMBRYO PRODUCTION USING IN VIVO-MATURED OOCYTES COLLECTED TRANSVAGINALLY FROM WOOD BISON (BISON BISON ATHABASCAE)

Reproductive technologies are being developed to help conserve the genetic diversity of wood bison, a threatened species. To date, the efficiency of in vitro embryo production in bison is very low and appears to be related to inadequate in vitro conditions for oocyte maturation. Recently, we have attempted to circumvent the problem by inducing oocyte maturation in vivo and found that more than one-third of superstimulated oocytes collected 30 h after administration of hCG were at metaphase II (Cervantes et al. 2013 Reprod. Fertil. Dev. 25, 283; Cervantes et al. 2014 Reprod. Fertil. Dev. 26, 199). We hypothesise that additional maturation time in vitro, after in vivo maturation, will allow the remaining oocytes to reach the MII stage, and thus improve in vitro embryo production in wood bison. The objective of this study was to determine the effect of an additional 4 h of in vitro maturation on the developmental competence of oocytes collected 30 h after hCG treatment. Wood bison cows (n = 24) were superstimulated by the administration of 300 mg of FSH (Folltropin-V) diluted in 0.05% hyaluronan on the day of follicular wave emergence and 100 mg of FSH in hyaluronan 2 days later. Bison were administered 2500 IU of hCG (Chorulon) IM 2 days after the last dose of FSH. Transvaginal ultrasound-guided follicle aspiration was performed 30 h after hCG treatment to collect cumulus-oocyte complexes (COC). Expanded COC (with no evidence of degeneration) were selected and assigned randomly to 2 groups (n = 38 COC/group) in which IVF was done immediately, or after 4 h of in vitro maturation in TCM 199 with 5% calf serum, 5 μg mL–1 pLH, 0.5 μg mL–1 pFSH, and 0.05 μg mL–1 gentamicin, at 38.5°C, 5% CO2 and high humidity. In vitro fertilization (Day 0) was done with frozen-thawed wood bison semen (dose 5 × 106 sperm mL–1) in Brackett-Oliphant medium at 38.5°C, 5% CO2, and high humidity. Presumptive zygotes were cultured in CR1aa plus 5% calf serum, at 38.5°C and in 5% CO2, 5% O2, and 90% N2 and high humidity. Cleavage was recorded on Day 3, and blastocyst formation was recorded on Days 7 and 8. Cleavage and blastocyst rates (calculated from the total number of oocytes submitted to IVF) were compared between groups by chi-square analysis. No difference was detected between groups (immediate fertilization v. after an additional 4 h in vitro) in cleavage rate on Day 3 (55.3 v. 60.5%, respectively, P = 0.82), or blastocyst rate on Day 7 (13.2 v. 23.7%, respectively, P = 0.37). However, the blastocyst rate on Day 8 was higher in the COC group exposed to an additional 4 h of in vitro maturation (18.4 v. 44.7%, respectively, P = 0.03). Results support the hypothesis that an additional short period of in vitro maturation improves the developmental competence of oocytes collected after 30 h of in vivo maturation.We thank Bioniche Animal Health for providing FSH (Folltropin-V) and hyaluronan (MAP-5), and Merck Animal Health for hCG (Chorulon).

38 EFFECT OF OOCYTE MATURATION DURATION ON BLASTOCYST RATES AFTER EQUINE SOMATIC CELL NUCLEAR TRANSFER

In equine cloning, the scarcity of equine oocytes places emphasis on development of the most efficient nuclear transfer (NT) methods possible. In other species, using oocytes matured for the shortest duration needed to reach metaphase II has increased NT efficiency. In the present study, we examined the effect of duration of oocyte maturation at the time of enucleation on equine cloned blastocyst production. Oocytes were collected from live mares by transvaginal ultrasound-guided aspiration of all visible follicles ≥5 mm in diameter. The oocytes were held overnight (16–22 h) at room temperature, matured in vitro, and reconstructed with donor cells as described in our previous study (Choi et al. 2013 Theriogenology 79, 791–796). In Experiment 1, oocytes were divided into 2 groups and matured for 20 or 24 h. After enucleation, oocytes were reconstructed by direct injection of donor cells. Reconstructed oocytes were held for 5 h and then activated by treatment with 5 μM ionomycin for 4 min, then injection with sperm extract, followed by incubation in 2 mM 6-DMAP for 4 h. The activated reconstructed oocytes were cultured in global human embryo culture medium under 5% CO2, 6% O2, and 89% N2 at 38.2°C for 7 to 11 days (20 mM glucose was added at Day 5) and blastocyst rate was recorded. Because a low maturation rate was found at 20 h in Experiment 1, in Experiment 2 oocytes were denuded at 20 h and those that were mature were enucleated and used for NT; those that had not cast out a polar body at 20 h were cultured for an additional 3 h (20 + 3h) and then evaluated for polar body formation and used for NT, which was conducted as in Experiment 1. Data were analysed by Fisher's exact test. In Experiment 1, 203 oocytes were collected in 46 aspiration sessions. The rate of oocyte maturation to metaphase II was significantly lower for oocytes cultured for 20 h (35/116, 30%), than for those cultured for 24 h (47/80, 59%). However, the rate of blastocyst development was significantly higher for oocytes cultured for 20 h (11/27, 41%) than for 24 h (2/38, 5%). In Experiment 2, 89 oocytes were collected in 18 aspiration sessions. After 20 h of maturation culture, 22 oocytes were mature (25%). After an additional 3 h of culture, 21 additional oocytes had matured. There were no significant differences between the two treatments (20 and 20 + 3h) in reconstruction rates (77%, 17/22, and 90%, 19/21, respectively) or blastocyst rates (24%, 4/17, and 32%, 6/19, respectively). These results indicate that duration of in vitro maturation, or the duration of presence of cumulus cells, influences blastocyst development after somatic cell NT in the horse. This appears to be due to a benefit of using oocytes immediately after they reach metaphase II; if this is ensured as in Experiment 2, the duration of maturation itself had no effect.This work was supported by the American Quarter Horse Foundation, the Link Equine Research Endowment Fund, Texas A&amp;M University, and by Ms. Kit Knotts.

Pregnancy rates in criollo breed mares after ultrasound-guided follicular aspiration

There are few studies about transvaginal ultrasound-guided follicle aspiration in equine medicine regarding potential complications to future fertility of aspirated mares. In order to evaluate the effect of follicular aspiration on subsequent fertility in mares, two experiments were conducted. In Experiment I, fifteen Criollo mares were allocated to one of three groups according to the diameter of the aspirated follicle during estrus: 25-29mm (n=4; Group 1); 30-34mm (n=6; Group 2); &gt; 35mm (n=5; Group 3) and control group (n=15; Group 4). In Experiment II, the follicular aspiration was attempted in twenty-five mares during diestrous, when at least four follicles (&gt; 5mm) were seen in the transrectal ultrasonography of both ovaries. All visible follicles, between 4 and 8 mm, were aspirated. Thirty-one mares served as control. In Experiments I and II, the pregnancy rates in the following cycle after aspiration were 75.0% (Group 1), 83.3% (Group 2), 60.0% (Group 3), and 73.3% (Group 4 - Control); and 76.0% in the aspirated diestrous group and 77.4% in the control group (non aspirated), respectively. On both experiments, pregnancy rates were similar (P&gt;0.05) in treated and control mares. The results of this study show that the conception rates of the first estrus period following follicular aspiration are not affected by the procedure.