Interaction energy flow paths analysis of PMSG-based wind power integrated systems during LVRT and its parameter adjustment strategy.

To solve the problem of oscillation instability in permanent magnetic synchronous generator (PMSG)-based wind power connected systems during low-voltage ride through (LVRT) process, a parameter adjustment strategy based on interaction energy path optimization is proposed in this paper. Firstly, a modular state-space model of PMSG under fault transient conditions is constructed, and the system is divided into five subsystems. Then, the dynamic energy function of subsystems reflecting the oscillation stability of the system is derived. Based on that, the dynamic energy flow path is described considering the introduction of LVRT control. On this basis, the interaction energy between LVRT control links and subsystems is analyzed, and the coupling mechanism of voltage support and damping characteristics in the LVRT process is explained. Further, aiming at the optimal change rate of the total interaction energy in the LVRT process, the adjustment strategy of LVRT control parameters is constructed to meet voltage and damping requirements. Finally, a PMSG-connected system model is built on the MATLAB/Simulink platform to verify the effectiveness of the adjustment strategy. The results show that the proposed method can effectively improve the damping level under the fault transient condition, as well as supporting system voltage.

The Utility of Three-Dimensional Printing in Physician-Modified Stent Grafts for Aortic Lesions Repair.

Background: Three-dimensional (3D) printing is becoming increasingly popular around the world not only in engineering but also in the medical industry. This trend is visible, especially in aortic modeling for both training and treatment purposes. As a result of advancements in 3D technology, patients can be offered personalized treatment of aortic lesions via physician-modified stent grafts (PMSG), which can be tailored to the specific vascular conditions of the patient. The objective of this systematic review was to investigate the utility of 3D printing in PMSG in aortic lesion repair by examining procedure time and complications. Methods: The systematic review has been performed using the PRISMA 2020 Checklist and PRISMA 2020 flow diagram and following the Cochrane Handbook. The systematic review has been registered in the International Prospective Register of Systematic Reviews: CRD42024526950. Results: Five studies with a total number of 172 patients were included in the final review. The mean operation time was 249.95± 70.03 min, and the mean modification time was 65.38 ± 10.59 min. The analysis of the results indicated I2 of 99% and 100% indicating high heterogeneity among studies. The bias assessment indicated the moderate quality of the included research. Conclusions: The noticeable variance in the reviewed studies' results marks the need for larger randomized trials as clinical results of 3D printing in PMSG have great potential for patients with aortic lesions in both elective and urgent procedures.

Experimental investigation of a real-time singularity-based fault diagnosis method for five-phase PMSG-based tidal current applications.

This paper presents a novel real-time singularity-based fault diagnosis method for tidal current applications, specifically utilizing a five-phase permanent magnet synchronous generator with trapezoidal back electromotive forces. The proposed method incorporates an innovative orthogonal signal generator through a second-order filter, enabling the extraction of detectable singularity signatures from phase current signals. The principle of the method is elucidated through step-by-step design procedures, outlining the indicator enhancement approach and adaptive thresholds employed for enhanced robustness and adaptability. Fault detection is performed based on the improved fault indicators and an adaptive threshold law, followed by immediate fault localization that is achieved via twice average operations of the phase currents. To demonstrate the effectiveness and efficiency of the proposed method, a comparative study is carried out with a classical mean current vector-based fault diagnosis method. A small-scale experimental platform emulating a tidal current application is established for a comprehensive evaluation of both methods. The experimental results highlight the superior fault diagnosis performance of the proposed method, particularly in detecting single and multiple open circuit faults in phases or switches, while exhibiting enhanced robustness against variations in torque and speed. The simplicity of implementation and rapid detection mechanism are principal merits for the proposed method.

Effects of Au@Ag core-shell nanostructure with alginate coating on male reproductive system in mice.

Despite the widespread use of silver nanoparticles (NPs), these NPs can accumulate and have toxic effects on various organs. However, the effects of silver nanostructures (Ag-NS) with alginate coating on the male reproductive system have not been studied. Therefore, this study aimed to investigate the impacts of this NS on sperm function and testicular structure. After the synthesis and characterization of Ag-NS, the animals were divided into five groups (n = 8), including one control group, two sham groups (received 1.5 mg/kg/day alginate solution for 14 and 35 days), and two treatment groups (received Ag-NS at the same dose and time). Following injections, sperm parameters, apoptosis, and autophagy were analyzed by the TUNEL assay and measurement of the mRNA expression of Bax, Bcl-2, caspase-3, LC3, and Beclin-1. Fertilization rate was assessed by in vitro fertilization (IVF), and testicular structure was analyzed using the TUNEL assay and hematoxylin and eosin (H&E) staining. The results showed that the NS was rod-shaped, had a size of about 60 nm, and could reduce sperm function and fertility. Gene expression results demonstrated an increase in the apoptotic markers and a decrease in autophagy markers, indicating apoptotic cell death. Moreover, Ag-NS invaded testicular tissues, especially in the chronic phase (35 days), resulting in tissue alteration and epithelium disintegration. The results suggest that sperm parameters and fertility were affected. In addition, NS has negative influences on testicular tissues, causing infertility in men exposed to these NS.

Influence of PMSG on Superstimulation and Embryo Development Following Somatic Cell Nuclear Transfer in Holstein Cows in the United Arab Emirates.

The present study investigated the effect of superstimulation to improve in vitro embryo production in the Gulf area, where the temperature is high. Holstein cows were classified into the control and superstimulation groups. Superstimulation was induced with a single intramuscular injection of pregnant mare serum gonadotropin (PMSG; 2500 IU) on day 14 of the estrus cycle (day 0; estrus). The development of follicles was evaluated by ultrasonography of the ovaries daily. At 40 h after the PMSG injection, oocytes were collected by the ovum pick-up (OPU) technique. OPU was performed at the same stage of the estrus cycle in the control group as in the superstimulation group. The number of follicles with a diameter of more than 6 mm and the number of retrieved cumulus-oocyte complexes were significantly higher in the superstimulation group than in the control group. Furthermore, the maturation rate was higher in the superstimulation group than in the control group. Cloned embryos were produced by somatic cell nuclear transfer using matured oocytes. The cleavage and blastocyst formation rates were significantly higher in the superstimulation group than in the control group. In conclusion, a single injection of PMSG can facilitate the efficient production of cloned cow embryos.

Genetic algorithm optimized robust nonlinear observer for a wind turbine system based on permanent magnet synchronous generator.

This paper presents an optimal control scheme for a Permanent Magnet Synchronous Generator (PMSG) coupled to a wind turbine operating without a position sensor. This sensorless scheme includes two observers: The first observer uses the flux to estimate the speed. However, an increase in the temperature or a degradation of the permanent magnet characteristics will result in a demagnetization of the machine causing a drop in the flux. The second observer is therefore used to estimate these changes in the flux from the speed and guaranties the stability of the system. This structure leads to a better exchange of information between the two observers, eliminates the problem of encoder and compensates for the demagnetization problem. To improve the precision of the speed estimator, the gain of the non-linear observer is optimized using Genetic Algorithm (GA) and the speed is obtained from a modified Phase Locked Loop (PLL) method using an optimized Sliding Mode Controller (SMC). Furthermore, to enhance the convergence speed of this observer scheme and improve the performance of the system a Fast Super Twisting Sliding Mode Control (FSTSMC) is introduced to reinforce the SMC strategy. A series of simulations are presented to show the effectiveness and robustness of proposed observer scheme.

Determining the Effects of Serial Injections of Pregnant Mare Serum Gonadotropin on Plasma Testosterone Concentrations, Testicular Dynamics, and Semen Production in Leopard Geckos (Eublepharis macularius).

Reptiles are highly susceptible to anthropogenic activities as a result of their narrow geographical ranges and habitat specialization, making them a conservation concern. Geckos represent one of the mega-diverse reptile lineages under pressure; however, limited assisted reproductive technologies currently exist for these animals. Exogenous pregnant mare serum gonadotropin (PMSG) has been found to exhibit follicle stimulating hormone-like action and has been routinely used to alter reproductive hormones of vertebrates in assisted reproductive protocols. The purpose of this study was to determine the effects of serial injections of 20 IU and 50 IU PMSG on circulating testosterone concentrations, testicular dynamics, and semen production in a model species of gecko. Twenty-four captive-bred, adult, male leopard geckos (Eublepharis macularius) were divided into three treatment groups and administered a once-weekly injection of either PMSG or saline for a total of nine weeks. Ultrasonographic testicular measurements, electrostimulation for semen collection, and venipuncture were performed on days 0, 21, 42, and 63. Right unilateral orchidectomies and epididymectomies were performed in all animals on day 63; tissues were submitted for histopathology. PMSG treated geckos had significantly higher testicular volumes and weights, spermatozoa motility, and spermatozoa concentrations compared with controls. However, there were no significant differences in testosterone concentrations by treatment or time. Under the conditions outlined, PMSG is effective at stimulating spermatogenesis and increasing testicular size, but not effective at increasing testosterone concentrations in the leopard gecko between October-December in the Northern hemisphere.

Recommendations for Ensuring Good Welfare of Horses Used for Industrial Blood, Serum, or Urine Production.

Various pharmaceutical products have been derived from horse blood and urine for over a century. Production of biologics and therapeutics from these samples is a niche industry and often occurs in regions with little regulation or veterinary oversight. To ensure good welfare of horses maintained for these purposes, guidance has been developed to support the industry.

Development of a suitable manufacturing process for production of a bioactive recombinant equine chorionic gonadotropin (reCG) in CHO-K1 cells.

Equine chorionic gonadotropin (eCG) is a heterodimeric glycoprotein hormone produced by pregnant mares that has been used to improve reproductive performance in different domestic species. Several strategies to produce the hormone in a recombinant way have been reported; nevertheless, no approach has been able to produce a recombinant eCG (reCG) with significant in vivo bioactivity or in sufficient quantities for commercial purposes. For this reason, the only current product available on the market consists of partially purified preparations from serum of pregnant mares (PMSG). Herein, we describe a highly efficient process based on third-generation lentiviral vectors as delivery method for the production of reCG in suspension CHO-K1 cells, with productivities above 20 IU 106 cell-1.d-1 and 70% purification yields after one purification step. Importantly, reCG demonstrated biological activity in cattle, since around 30 µg of reCG were needed to exert the same biologic effect of 400 IU of PMSG in an ovulation synchronization protocol. The results obtained demonstrate that the developed strategy represents an attractive option for the production of reCG and constitutes an auspicious alternative for the replacement of animals as a source of PMSG.

A systematic review of three-dimensional printed template-assisted physician-modified stent grafts for fenestrated endovascular aneurysm repair.

OBJECTIVE: Fenestrated endovascular aneurysm repair has yet to gain widespread adoption owing to the technical complexity and increased risk of complications. Three-dimensional (3D) printed templates to guide fenestrated physician-modified stent grafts (PMSGs) are a novel technique that may have the potential to increase the accuracy of fenestration alignment, and to disrupt both the cost and timing of the current commercial fenestrated endograft supply chain. We have conducted a critical appraisal of the emerging literature to assess this. METHODS: A systematic literature search was performed using PubMed and OVID Medline as guided by the PRISMA statement on April 30, 2020. We used "3D printing" and "physician modified" or "surgeon modified" and all related search terms. We identified 50 articles which met our search criteria. None articles were included as being of direct relevance to 3D-printed template-assisted PMSGs for fenestrated endovascular aneurysm repair. Abstracts were screened individually by each investigator to ensure relevance. RESULTS: Nine relevant articles were identified for critical analysis. These included one technical report, five case reports or series, two prospective trials, and one letter to the editor. CONCLUSIONS: These 3D-printed templates are a promising new avenue to assist with the placement of fenestrations in PMSGs, particularly in urgent or emergent cases where custom fenestrated endografts are unavailable, with larger scale studies warranted. Further work to validate the key stages of the template workflow are required, as well as further investigation into the most suitable manufacturing and distribution methods before the mainstream implementation of this novel technique.

Ovarian superstimulatory response and embryo development using a new recombinant glycoprotein with eCG-like activity in mice.

Pharmacological ovarian control required for the implementation of artificial insemination and embryo-related technologies usually includes the use of eCG, naturally produced in pregnant mares. In this study, we report the superovulatory response and embryo development in mice obtained with a new glycoprotein with eCG-like activity (reCG) produced by recombinant DNA technology. A total of 150 females from three different mouse strains (C57BL/6J, BALB/cJ and B6D2F1/J) were subjected to a superstimulatory protocol consisting of 5 IU of natural eCG (n = 50), 5 IU of reCG (n = 50), or received a placebo (no-eCG, n = 50) by intraperitoneal route, followed by 5 IU of human chorionic gonadotropin 48 h later. Overall, no significant differences were observed in the total number of ova/zygotes (33.6 ± 2.4 vs 28.7 ± 2.6; P = NS) and viable ova/zygotes (31.5 ± 2.4 vs 25.8 ± 2.5; P = NS) collected per female among eCG and reCG treated females, respectively, which were greater (P < 0.05) than those obtained in no-eCG treated females (6.9 ± 0.7 and 5.9 ± 0.7, respectively). Zygotes derived from the three experimental groups (n = 2914) were subjected to in vitro culture until hatching 4.5 days post coitum (dpc). Regardless of the mouse strain, no differences were observed among eCG and reCG treated females for overall cleavage rate 1.5 dpc (58.5% vs 60.5%), development rate 3.5 dpc (47.2% vs 48.9%) and hatching rate 4.5 dpc (49.5% vs 54.5) (P = NS). Control females from no-eCG treated group showed lower cleavage and development rates (36.4% and 29.7%, respectively; P < 0.05). In conclusion, this study reports for the first time comparable superovulatory response and embryo development between recombinant and natural eCG treatment, which has important implications for reproductive technologies in several species.

A Distributed Control Scheme Using SiC-Based Low Voltage Ride-Through Compensator for Wind Turbine Generators.

As the penetration of renewable energy power generation, such as wind power generation, increases low voltage ride-through (LVRT), control is necessary during grid faults to support wind turbine generators (WTGs) in compensating reactive current to restore nominal grid voltages, and maintain a desired system stability. In contrast to the commonly used centralized LVRT controller, this study proposes a distributed control scheme using a LVRT compensator (LVRTC) capable of simultaneously performing reactive current compensation for doubly-fed induction generator (DFIG)-, or permanent magnet synchronous generator (PMSG)-based WTGs. The proposed LVRTC using silicon carbide (SiC)-based inverters can achieve better system efficiency, and increase system reliability. The proposed LVRTC adopts a digital control scheme and dq-axis current decoupling algorithm to realize simultaneous active/reactive power control features. Theoretical analysis, derivation of mathematical models, and design of the control scheme are initially conducted, and simulation is then performed in a computer software environment to validate the feasibility of the system. Finally, a 2 kVA small-scale hardware system with TI's digital signal processor (DSP) as the control core is implemented for experimental verification. Results from simulation and implementation are in close agreement, and validate the feasibility and effectiveness of the proposed control scheme.

Eremomastax speciosa potentializes the PMSG-inducing effect on some physiological and biochemical parameters in PMSG-primed immature rats.

The present study evaluated the effect of the aqueous extract from leaves of E. speciosa on some physiological and biochemical parameters of reproduction and the onset of puberty in pregnant mare serum gonadotropin (PMSG)-primed immature female rats. High pressure liquid chromatography (HPLC) was used to quantify the phenolic compounds in the methanol/methylene chloride (1:1) extract, the ethanolic and ethyl acetate fractions and the aqueous residue of E. speciosa. E. speciosa (0, 8, 32 or 64 mg/kg) were administered for 15 days to 24 non-PMSG-primed and 24 primed rats with 0.01 IU of PMSG. At the end of the treatment period, animal were sacrificed and their body, ovarian, uterine weight, ovarian protein or cholesterol level, as well as data on puberty onset were recorded. Of the 16 polyphenolic compounds quantitatively revealed in the extracts and fractions of E. speciosa after HPLC analysis, quercetin, rutin, apigenin and eugenol were the most abundant. Non-primed rats showed a significant increase (P < 0.05) in the uterine relative weight at the dose of 8 mg/kg when compared with the other treatments. The uterine proteins and the ovarian cholesterol (P < 0.05), respectively, showed a reduction at doses of 64 mg/kg and 32 mg/kg in non-primed rats. However in PMSG-primed rats, a significant decrease (P < 0.05) was observed in ovarian cholesterol at 64 mg/kg. In conclusion, E. speciosa potentializes the PMSG-inducing effect on folliculogenesis in PMSG-primed rats.

Characterization of organic anion transporting polypeptide 1b2 knockout rats generated by CRISPR/Cas9: a novel model for drug transport and hyperbilirubinemia disease.

Organic anion transporting polypeptide 1B1 and 1B3 (OATP1B1/3) as important uptake transporters play a fundamental role in the transportation of exogenous drugs and endogenous substances into cells. Rat OATP1B2, encoded by the Slco1b2 gene, is homologous to human OATP1B1/3. Although OATP1B1/3 is very important, few animal models can be used to study its properties. In this report, we successfully constructed the Slco1b2 knockout (KO) rat model via using the CRISPR/Cas9 technology for the first time. The novel rat model showed the absence of OATP1B2 protein expression, with no off-target effects as well as compensatory regulation of other transporters. Further pharmacokinetic study of pitavastatin, a typical substrate of OATP1B2, confirmed the OATP1B2 function was absent. Since bilirubin and bile acids are the substrates of OATP1B2, the contents of total bilirubin, direct bilirubin, indirect bilirubin, and total bile acids in serum are significantly higher in Slco1b2 KO rats than the data of wild-type rats. These results are consistent with the symptoms caused by the absence of OATP1B1/3 in Rotor syndrome. Therefore, this rat model is not only a powerful tool for the study of OATP1B2-mediated drug transportation, but also a good disease model to study hyperbilirubinemia-related diseases.

Decreased ascorbic acid biosynthesis in response to PMSG in the pre-pubertal female rat ovary.

Ascorbic acid (AA) is known to be an important antioxidant serving as a cofactor in collagen synthesis, and thus facilitates follicular growth in the ovary. Many studies have shown that AA is synthesized in the liver and transported to other organs including ovary, however, there is no direct evidence of ascorbic acid synthesis in the ovary. Hence, we examined the expression pattern of different proteins (SMP30/GNL and GULO) involved in the AA synthesis in pre-pubertal rat, which showed significant expression of these proteins, suggesting the synthesis of AA in the ovary. Accumulation of AA in the ovary during follicular growth has been well demonstrated. However, the effect of Pregnant Mare Serum Gonadotropin (PMSG) on the AA synthesis in the ovary has not been studied in detail. Hence to decipher the effect, different doses of PMSG were injected subcutaneously into the pre-pubertal female rats, and ovarian AA level was measured after 48 h. A significant increase in AA content was observed in PMSG treated animal groups. Further, to understand the mechanism underlying ovarian AA accumulation, the expression levels of SMP30/GNL and GULO genes were measured. Expression of both the genes was significantly suppressed, which suggested a lowered AA synthesis in the PMSG treated rat ovary. For further understanding, mRNA expression of AA transporters SVCT1 and SVCT2 encoded by SLC23A1 and SLC23A2 genes respectively were measured, which showed increased level of SVCT1 expression. These observations suggested that the increased AA content might not be due to increased synthesis of AA within the ovary but possibly due to increased uptake from blood during the stimulation of follicular growth.

Modification of i-GONAD Suitable for Production of Genome-Edited C57BL/6 Inbred Mouse Strain.

Improved genome editing via oviductal nucleic acid delivery (i-GONAD) is a novel method for producing genome-edited mice in the absence of ex vivo handling of zygotes. i-GONAD involves the intraoviductal injection of clustered regularly interspaced short palindromic repeats (CRISPR) ribonucleoproteins via the oviductal wall of pregnant females at 0.7 days post-coitum, followed by in vivo electroporation (EP). Unlike outbred Institute of Cancer Research (ICR) and hybrid mouse strains, genome editing of the most widely used C57BL/6J (B6) strain with i-GONAD has been considered difficult but, recently, setting a constant current of 100 mA upon EP enabled successful i-GONAD in this strain. Unfortunately, the most widely used electroporators employ a constant voltage, and thus we explored conditions allowing the generation of a 100 mA current using two electroporators: NEPA21 (Nepa Gene Co., Ltd.) and GEB15 (BEX Co., Ltd.). When the current and resistance were set to 40 V and 350-400 Ω, respectively, the current was fixed to 100 mA. Another problem in using B6 mice for i-GONAD is the difficulty in obtaining pregnant B6 females consistently because estrous females often fail to be found. A single intraperitoneal injection of low-dose pregnant mare's serum gonadotrophin (PMSG) led to synchronization of the estrous cycle of these mice. Consequently, approximately 51% of B6 females had plugs upon mating with males 2 days after PMSG administration, which contrasts with the case (≈26%) when B6 females were subjected to natural mating. i-GONAD performed on PMSG-treated pregnant B6 females under conditions of average resistance of 367 Ω and average voltage of 116 mA resulted in the production of pregnant females at a rate of 56% (5/9 mice), from which 23 fetuses were successfully delivered. Nine (39%) of these fetuses exhibited successful genome editing at the target locus.

Quality of Preovulatory (GV) Oocytes in Mice after Injection of eCG at Various Stages of the Estrous Cycle.

We studied the influence of the estrous cycle on the morphology of preovulatory (germinal vesicle, GV) oocytes in mice and their capacity to meiotic maturation in vitro. After standard injections of eCG gonadotropin (PMSG, Follimag) to females at different stages of the estrous cycle, the maximum levels of GV oocytes (26±1/mouse) were isolated from the ovaries of animals injected with the hormone during estrus. The capacity of isolated GV oocytes to meiotic maturation in vitro decreased in the following order: estrus (75.5±2.3%), metestrus (67.9±3.4%), proestrus (57.8±4.4%), and diestrus (50.6±5.6%); the differences between estrus and diestrus/proestrus were significant (p<0.05). After eCG injections during estrus, GV oocytes differed from other oocytes by lesser total diameter, lesser diameter of cytoplasm, lesser thickness of zona pellucida, and moderately dilated perivitelline space. These signs reflected higher competence of the "estrous" GV oocytes for meiotic maturation in vitro. Hormone stimulation of females with eCG, with consideration for the stage of the estrous cycle, seems to be an effective method for improving the quality of GV oocytes isolated from mouse ovaries.

Treatment of male goats with equine chorionic gonadotrophin during the non-breeding season does not affect their sperm characteristics during the subsequent breeding season.

Equine chorionic gonadotrophin (eCG) is a hormone having FSH/LH effects. It can be used to enhance sperm quality in male goats (bucks) during the non-breeding season. In a previous study carried out during the non-breeding season, we treated ten bucks with eCG (leaving nine untreated animals as control). Over a 20-day period, the treated bucks received an initial dose of 800 IU of eCG, followed by four doses of 500 IU. We found eCG enhanced semen quality, however, as also happens in female goats (does), eCG also induced a high titer of anti-eCG antibodies. In does, this lowers fertility. The aim of the present study was to determine if the eCG treatment carried out on bucks during the non-breeding season had any negative effects on their reproductive status during the following breeding season. We measured serum concentration of testosterone and anti-eCG antibody, as well as key testicular and seminal characteristics. This study commenced 91 days after the final dose of eCG in the previous study. The anti-eCG titer was higher in the treatment bucks than in untreated ones (181.7 ± 61.3 ng/µL vs 31.1 ± 10.7 ng/µL; P < 0.05). However, there were no significant differences between treated and untreated bucks in testosterone concentration, scrotal circumference, testes pixel intensity, fresh and thawed semen characteristics, or sperm cryoresistance. So, although the eCG-treated bucks had greater titers of anti-eCG antibodies, their reproductive pattern was unaffected.

Horse Welfare During Equine Chorionic Gonadotropin (eCG) Production.

Collection of blood from pregnant mares for extraction of equine chorionic gonadotropin (eCG) is a critical but relatively unknown and poorly regulated practice in the countries in which it occurs. Equine chorionic gonadotropin is a hormone that is widely used to enhance reproductive performance and management of dairy and beef cattle, sheep, goats, and pigs kept under intensive housing systems. eCG is extracted from the blood of brood mares between days 40-120 of gestation. Although alternatives have been sought, there is currently no efficacious replacement, natural or synthetic, for eCG. Recently, several animal welfare organizations have voiced concerns over the condition and treatment of pregnant mares kept for eCG production in some countries. Animal welfare issues may arise if mares are bled too frequently or if too much blood is collected at any time. In addition, these mares tend to be managed extensively on pastures with minimal veterinary oversight and they may be poorly desensitized and habituated to handling and other practices. This can lead to serious injuries and even death when mares are brought in for bleeding. This paper reviews the process of blood collection for eCG extraction and provides recommendations for ensuring mare welfare.

Comparative Analysis of Number and Competence in Meiotic Maturation of Preovulatory Oocytes of C57Bl/6J Mice and Their F1 Hybrids after Stimulation with Gonadotropin.

The study examined maturation of preovulatory germinal vesicles oocytes (GV oocytes) induced by gonadotropic hormone PMSG in the inbred C57Bl/6J mice (viewed as a gold standard for diverse biomedical studies) as well as in the first generation hybrid C57Bl/6J×СВА/lac and СВА/lac×C57Bl/6J mice at various ages. The most effective donors of GV oocytes were СВА/lac×C57Bl/6J mice (F1 hybrids) yielding 25±2 oocyte/mouse. In contrast, a significantly smaller number of GV oocytes can be isolated from the ovaries of female C57Bl/6J or C57Bl/6J×СВА/lac mice under the same conditions. At this, the greatest number of GV oocytes (42±4) can be retrieved from the ovaries of immature hybrid СВА/lac×C57Bl/6J mice aged 4 weeks. These mice demonstrated the largest share of GV oocytes, which attained MII stage during in vitro culturing. The data conclude that F1 hybrid СВА/lac×C57Bl/6J mice can be viewed as a handy experimental source yielding a large number of GV oocytes capable of meiotic maturation in a culture.