Ethylene Glycol-based Solution Research Articles

A clinical comparison of glycol and water-based heater-cooler systems for cardiopulmonary bypass.

While newer heater-cooler technologies using ethylene glycol-based (GB) solutions during cardiothoracic surgery have become commercially available, there is a paucity of clinical data describing their effectiveness during cardiopulmonary bypass (CPB) support. This analysis aimed to compare clinical characteristics and procedural outcomes using water-based (WB) and GB heater-cooler systems. A retrospective analysis was performed on consecutive adult patients undergoing CPB from June to October 2022 comparing WB or GB groups. The primary outcome was a composite of operative death or major morbidity. Secondary endpoints included transfusion requirements on CPB, patient cooling and warming rates, and vasoactive-inotropic scores (VIS) at case completion. P-control charts were used to monitor the weekly incidence of the composite outcome. A sub-analysis was performed to evaluate the primary outcome for cardiac surgery cases indexed by the Society of Thoracic Surgeons (STS). There were 167 patients included for analysis; 87 (52.1%) underwent CPB with a WB system and 80 (47.9%) with a GB system. GB procedure subjects were younger (p = .01), experienced longer CPB times (p = .034), and were more likely to receive thoracic transplant or aortic surgery (p = 0.015). The composite outcome of operative mortality or major morbidity occurred in 29.9% and 24% of the WB and GB groups, respectively (p = .372). P-control charts indicated a weekly mean incidence of 30% during WB practice, which decreased to 24% with GB practice. Among 106 STS-indexed cardiac surgery cases, mean composite outcome incidence decreased from 19% to 6% following our GB transition. Additionally, cooling, and warming rates indexed to patient BSA and VIS at case completion were not significantly different. Our analysis demonstrated a safe transition from WB to GB heater-cooler technologies in our practice. This early analysis suggests that GB heater coolers may be safely adopted to mitigate the risks of nontuberculous mycobacterium infections for cardiac surgical patients.

Photoelectrochemical properties of anodic iron oxide layers

As a result of anodization, nanostructured iron oxide was obtained in an unstirred ethylene glycol-based solution with 0.2 M NH4F and 0.5 M H2O. The morphology of the obtained materials was characterized and correlated with the applied potential used for electrosynthesis. The performed XRD analysis enabled the identification of iron oxide crystalline phases (hematite, magnetite) obtained as a result of material annealing at 400 °C. The correlations between oxide layer thicknesses, maximal IPCE values obtained at the potential of 0.3 V vs. SCE, and estimated donor densities for anodic samples formed at different anodizing potentials were observed. All the tested electrodes are capable to generate an anodic photocurrent in the wavelength range from 200 to about 700 nm. It should be mentioned that the studied materials possess a narrow band gap energy (∼2.2 eV), which allows efficient visible light absorption.

Directly Anodized Sulfur-Doped TiO2 Nanotubes as Improved Anodes for Li-ion Batteries

TiO2 represents one of the promising anode materials for lithium ion batteries due to its high thermal and chemical stability, relatively high theoretical specific capacity and low cost. However, the electrochemical performance, particularly for mesoporous TiO2, is limited and must be further developed. Elemental doping is a viable route to enhance rate capability and discharge capacity of TiO2 anodes in Li-ion batteries. Usually, elemental doping requires elevated temperatures, which represents a challenge, particularly for sulfur as a dopant. In this work, S-doped TiO2 nanotubes were successfully synthesized in situ during the electrochemical anodization of a titanium substrate at room temperature. The electrochemical anodization bath represented an ethylene glycol-based solution containing NH4F along with Na2S2O5 as the sulfur source. The S-doped TiO2 anodes demonstrated a higher areal discharge capacity of 95 µAh·cm−2 at a current rate of 100 µA·cm−2 after 100 cycles, as compared to the pure TiO2 nanotubes (60 µAh·cm−2). S-TiO2 also exhibited a significantly improved rate capability up to 2500 µA·cm−2 as compared to undoped TiO2. The improved electrochemical performance, as compared to pure TiO2 nanotubes, is attributed to a lower impedance in S-doped TiO2 nanotubes (STNTs). Thus, the direct S-doping during the anodization process is a promising and cost-effective route towards improved TiO2 anodes for Li-ion batteries.

Development of assisted reproductive technologies for Mus spretus†.

The genus Mus consists of many species with high genetic diversity. However, only one species, Mus musculus (the laboratory mouse), is common in biomedical research. The unavailability of assisted reproductive technologies (ARTs) for other Mus species might be a major reason for their limited use in laboratories. Here, we devised ARTs for Mus spretus (the Algerian mouse), a commonly used wild-derived Mus species. We found that in vitro production of M. spretus embryos was difficult because of low efficacies of superovulation with equine chorionic gonadotropin or anti-inhibin serum (AIS) (5-8 oocytes per female) and a low fertilization rate following in vitro fertilization (IVF; 15.2%). The primary cause of this was the hardening of the zona pellucida but not the sperm's fertilizing ability, as revealed by reciprocal IVF with laboratory mice. The largest number of embryos (16 per female) were obtained when females were injected with AIS followed by human chorionic gonadotropin and estradiol injections 24h later, and then by natural mating. These in vivo-derived 2-cell embryos could be vitrified/warmed with a high survival rate (94%) using an ethylene glycol-based solution. Importantly, more than 60% of such embryos developed into healthy offspring following interspecific embryo transfer into (C57BL/6×C3H) F1 female mice. Thus, we have devised practical ARTs for Mus spretus mice, enabling efficient production of embryos and animals, with safe laboratory preservation of their strains. In addition, we have demonstrated that interspecific embryo transfer is possible in murine rodents.

A Photoelectrochemical Sensor Based on Anodic TiO2 for Glucose Determination.

A simple photoelectrochemical (PEC) sensor based on non-modified nanostructured anodic TiO2 was fabricated and used for a rapid and sensitive detection of glucose. The anodic TiO2 layers were synthesized in an ethylene glycol-based solution containing NH4F (0.38 wt.%) and H2O (1.79 wt.%) via a three-step procedure carried out at the constant voltage of 40 V at 20 °C. At the applied potentials of 0.2, 0.5, and 1 V vs. saturated calomel electrode (SCE), the developed sensor exhibited a photoelectochemical response toward the oxidation of glucose, and two linear ranges in calibration plots were observed. The highest sensitivity of 0.237 µA µmol−1 cm−2 was estimated for the applied bias of 1 V. The lowest limit of detection (LOD) was obtained for the potential of 0.5 V vs. SCE (7.8 mM) with the fastest response at ~3 s. Moreover, the proposed PEC sensor exhibited relatively high sensibility, good reproducibility, and due to its self-cleaning properties, a good long-term stability. Interfering tests showed the selective response of the sensor in the presence of urea and uric acid. Real-life sample analyses were performed using an intravenous glucose solution, which confirmed the possibility of determining the concentration of analyte in such types of samples.

Electrodeposition of cobalt thin films and nanowires from ethylene glycol-based solution

Ethylene glycol-based solutions containing metal precursor chloride salts were investigated for the electrodeposition of cobalt thin films and nanowires. The electrochemical behavior of 0.5 M Co(II) chloride solution at 70 °C was studied by means of cyclic voltammetry (CV) on a Pt substrate. The reduction process was shown to be irreversible, with high faradaic efficiencies (85–90 %). A diffusion coefficient (D0) of 2.29 × 10−6 cm2 s−1 for the Co species was estimated from the electrochemical behavior at different scan rates (from 25 to 125 mV s−1). The electrodeposition process was also studied on a copper substrate at different cathodic potentials (from −0.75 V vs Pt to −0.95 V vs Pt). Field-emission scanning electron microscopy (FE-SEM) and electron dispersive spectroscopy (EDS) revealed high-purity, compact films. Template-assisted electrodeposition resulted in ~16–18 μm long cobalt nanowires with an aspect ratio L/D > 100. X-ray diffraction (XRD) analysis of Co thin films showed a preferential orientation along the HCP [100] direction, which was even more marked for the nanowires. Vibrating sample magnetometry (VSM) highlighted that the fact that Co thin films were magnetized in-plane, while in nanowires a competition between shape and magnetocrystalline anisotropy led to similar magnetic behavior for the in-plane and out-of-plane directions.

Tailoring the morphology of nanotubular oxide layers on Ti-24Nb-4Zr-8Sn β-phase titanium alloy

In the present work, the self-organized mixed-oxide nanotubes (NTs) has been obtained on the Ti2448 β-phase alloy by electrochemical anodization process. NTs of 54–93 nm in diameter with different morphology can be obtained by tailoring the chemical composition of solution and anodization parameters. Well-ordered structures with both ribbed and smooth walls were fabricated. The most homogenous NTs were obtained as a result of anodization in ethylene glycol-based solution with 10% of water. The X-ray photoelectron spectroscopy and Auger electron spectroscopy results indicate that the obtained nanotubular layer mainly consists of the stoichiometric oxides TiO2 and Nb2O5 and a small amount of ZrO2 and SnO which are located throughout entire NTs height. The obtained NTs oxide layers exhibits superhydrophilic properties.

Electrical Behavior of a Nanoporous Nb2O5/Pt Schottky Contact at Elevated Temperatures

This paper discusses the effects of temperature on Schottky behavior of anodized niobium pentoxide (Nb2O5) used to form a nanoporous structure film. The application of a typical Schottky diode is limited at high temperature, and studies of different materials used in the fabrication are still in demand. Nb2O5 as a Schottky diode operation at elevated temperature has yet to be investigated. A nanoporous structure has the potential of producing high conductivity and also has the ability to spread heat since it has higher surface area. The structure was synthesized by anodizing niobium foils in ethylene glycol-based solution with 0.4 wt.% of H2O in different anodization times; 4 min, 8 min, 10 min, 40 min and 60 min. The anodized films were then annealed for 30 min at 440°C. The metal contact used for current–voltage (I–V) testing was platinum (Pt) and it was deposited via thermal evaporator at 30-nm thickness. Various characterization tests were conducted. Field emission scanning electron microscopy (FESEM) images suggested that longer anodization time produced larger pore sizes. The x-ray diffraction (XRD) confirmed the crystallization of Nb2O5 to be in an orthorhombic phase, while atomic force microscopy (AFM) showed surface roughness decreasing with longer anodization time. Higher surface roughness produced lower leakage current. I–V tests were conducted under different temperatures of 25°C, 50°C, 75°C, 100°C and 125°C to study the heat effect on I–V Schottky behavior of anodized nanoporous Nb2O5. By testing the I–V characteristics at elevated temperature, the electrical parameters were observed to have strong dependency on temperature. A device with lower thickness and operating at higher temperature produced higher current contribution. From I–V tests, it was observed that the increment of barrier height and decrement of ideality factor will be affected by increased temperature. For Schottky Pt/Nb2O5, barrier height increased in the range from 0.91 to 1.05, while the ideality factor decreased from 2.24 to 1.42.

Immobilization of the Alcohol Dehydrogenase Enzyme on TiO2 Nanotubes for Application in Microfluidic Fuel Cell

Microfluidic fuel cells are a low-power demand fuel cells which work without the need of a physical membrane and have a wide range of potential applications. Biological catalysts such as immobilized enzymes can be used in electrodes to carry out the oxidation processes of different organic fuels using the immobilization technology of enzymes; they are carried out under moderate conditions of pH and temperature, and the specificity of the catalytic reactions. The alcohol dehydrogenase enzyme has been used for the development of bioanodes for the oxidation of different alcohols such as ethanol and methanol. In this work, the immobilization of this enzyme was carried out using nanotubes of titanium dioxide for the development of electrodes for an air-breathing microfluidic fuel cell. TiO2 nanotubes has excellent properties such as pH resistance, superior mechanical strength, good biocompatibility making it a great candidate for the process of immobilization of the enzyme alcohol dehydrogenase. TiO2 nanotubes were fabricated by electrochemical anodic oxidation on Ti foils. The foils were pre-treated with sand-paper, thereafter immersed in ethanol, placed in ultrasonic bath, dried under N2 flow. An ethylene glycol-based solution with a concentration of 0.1M NH4F (96% purity, Alfa-Aesar) and 2% w/w deionized water was used as electrolyte. The anodization times used was 1 h with a voltage step of 60 V via a power source. Using this nanostructure, the enzymatic electrode was constructed using a catalityc ink with enzyme, tetrabutylammonium bromide and Nafion to carry out the immobilization process. We carried out the characterization of the electrode developed by means of different electrochemical and kinetic techniques, where it was demonstrated that the enzyme is present and active in the electrode, as well as its capacity to oxidize ethanol. Then the bioanode was evaluated in the microfluidic device also using an inorganic cathode of Pt / C, obtaining a good performance over an open circuit potential greater than 0.93V.

Growth of void-free Cu2ZnSn(S,Se)4 thin film by selenization Cu2ZnSnS4 precursor film from ethylene glycol-based solution

Solution method is promising in fabricating Cu2ZnSn(S,Se)4 (CZTSSe) thin-film solar cells, which could be economical and large-scale implementation, but highly toxic solvents have generally been involved. In this work, an ethylene glycol-based precursor solution method, which is simple and environmentally friendly, was newly designed for fabricating CZTSSe films. It was found that ethylene glycol was a suitable solvent for preparing CuZnSnS4 (CZTS) precursor film, which would be conducive to further applied in selenization processing at moderate temperatures (450°C, 500°C, 540°C). The effects of the selenization temperature on the microstructure, phase composition and photoelectronic properties of CZTSSe films were also investigated. The results reveal that the quality of CZTSSe films could be effectively promoted by selenization temperature, and the highly-crystallized and void-free CZTSSe films were obtained at 540°C, which may hold the promise for fabricating thin film solar cells.

Devising assisted reproductive technologies for wild-derived strains of mice: 37 strains from five subspecies of Mus musculus.

Wild-derived mice have long offered invaluable experimental models for mouse genetics because of their high evolutionary divergence from laboratory mice. A number of wild-derived strains are available from the RIKEN BioResource Center (BRC), but they have been maintained as living stocks because of the unavailability of assisted reproductive technology (ART). In this study, we sought to devise ART for 37 wild-derived strains from five subspecies of Mus musculus maintained at the BRC. Superovulation of females was effective (more than 15 oocytes per female) for 34 out of 37 strains by treatment with either equine chorionic gonadotropin or anti-inhibin serum, depending on their genetic background (subspecies). The collected oocytes could be fertilized in vitro at mean rates of 79.0% and 54.6% by the optimized protocol using fresh or frozen-thawed spermatozoa, respectively. They were cryopreserved at the 2-cell stage by vitrification with an ethylene glycol-based solution. In total, 94.6% of cryopreserved embryos survived the vitrification procedure and restored their normal morphology after warming. A conventional embryo transfer protocol could be applied to 25 out of the 35 strains tested. In the remaining 10 strains, live offspring could be obtained by a modified embryo transfer protocol using cyclosporin A treatment and co-transfer of ICR (laboratory mouse strain) embryos. Thus, ART for 37 wild-derived strains was devised successfully and is now routinely used for their preservation and transportation. The information provided here might facilitate broader use and wider distribution of wild-derived mice for biomedical research.

Equilibrium vitrification of mouse embryos at various developmental stages

Previously, we developed a new method by which 2-cell mouse embryos can be vitrified in liquid nitrogen in a near-equilibrium state, and then kept at -80°C for several days. In the present study, we examined whether or not the method was effective for mouse embryos at other developmental stages. Eight-cell embryos, morulae, and expanded blastocysts of ICR mice were vitrified with ethylene glycol-based solutions, named EFSc because of their composition of ethylene glycol (30-40%, v/v) and FSc solution. The FSc solution was PB1 medium containing 30% (w/v) Ficoll PM-70 plus 1.5 M sucrose. The extent of equilibrium was assessed by examining how well vitrified embryos survived after being kept at -80°C. When 8-cell embryos and morulae were vitrified with EFS35c or EFS40c and then kept at -80°C, the survival rate was high even after 4 days in storage and remained high after re-cooling in liquid nitrogen. On the other hand, the survival of vitrified-expanded blastocysts kept at -80°C was low. Therefore, 8-cell embryos and morulae can be vitrified in a near-equilibrium state using the same method as for 2-cell embryos. A high proportion of C57BL/6J embryos at the 2-cell, 8-cell, and morula stages vitrified with EFS35c developed to term after transportation on dry ice, re-cooling in liquid nitrogen, and transfer to recipients. In conclusion, the near-equilibrium vitrification method, which is effective for 2-cell mouse embryos, is also effective for embryos at the 8-cell and morula stages. The method would enable handy transportation of vitrified embryos using dry ice.

Neonatal outcome after vitrified day 3 embryo transfers: a preliminary study

To compare and evaluate the neonatal outcome in infants born after vitrified day 3 embryo transfers with that of fresh day 3 embryo transfers. Retrospective analysis. Private assisted reproductive center. Sixty-nine women, who delivered 89 babies. Surplus day 3 cleavage stage embryos were vitrified using ethylene glycol-based solution by cryoloop carrier system and transferred after warming. Post-thaw survival of embryos, implantation and pregnancy rates (PR), neonatal outcome, and congenital birth defects. A total of 907 vitrified day 3 embryos from 285 cycles were warmed and 817 survived (90.37%), which were used for embryo transfer. The pregnancy, implantation, miscarriage, and live birth rates achieved were 36.84%, 18.11%, 7.71%, and 24.21%, respectively. Of the 69 deliveries, singleton, twins, and triplets comprised of 72.46%, 26.08%, 1.44%, respectively, and 8 (11.59%) were preterm deliveries. The mean Apgar scores were 8.3, 9.2, 9.4 at 1, 5, and 10 minutes. The congenital birth defect rate was 1.18%. These results were comparable with pregnancies using fresh embryo transfers. This preliminary study shows that vitrification is an efficient method of cryopreservation of human day 3 embryos with neonatal outcome comparable to fresh embryo transfers.

Survival of frozen-thawed sheep embryos cryopreserved at cleavage stages

This study evaluated the effect of freezing-thawing procedures on the viability of sheep embryos cryopreserved at various developmental stages. The survival rates of frozen-thawed embryos were compared with non-frozen counterparts. Embryos were recovered from the oviduct and uterus, at different days of the early luteal phase, and were classified at six different developmental stages: 2- to 4-cell ( n = 72), 5- to 8-cell ( n = 73), 9- to 12-cell ( n = 70), early morulae ( n = 42), morulae ( n = 41), and blastocyst ( n = 70). For each early cleavage stage and blastocysts, approximately half of the embryos, were frozen immediately by slow freezing with an ethylene glycol-based solution. The remaining embryos were cultured to the hatched blastocyst stage. All morulae and compact morulae were frozen after recovery with the same protocol. Cryoprotectants were removed using 1 M sucrose solution, and then warmed the embryos were cultured to the hatched stage in a standardized in vitro culture. Embryo developmental stage had a significant effect on the ability to hatch following freezing ( P < 0.0001). The cryotolerance of the embryos fitted a regression ( r 2 = 0.908), increasing linearly from 2- to 4-cell embryos (17.1%) to morula stage (46.3%) and in a quadratic regression from the morula to the blastocyst stage (83.7%). Frozen early cleavage stage embryos had a significantly lower viability than their fresh counterparts (23.1 vs 83.1%; P < 0.0001), with a similar rate of viability between fresh or frozen blastocysts (92.5 vs 83.7%). In conclusion, early sheep embryos are very sensitive to freezing per se and the survival rates following conventional freezing improve as embryo developmental stage progresses.

Vitrification of rat embryos at various developmental stages

The effect of developmental stage on the survival of cryopreserved rat embryos was examined. Wistar rat embryos at various developmental stages were vitrified by a 1-step method with EFS40, an ethylene glycol-based solution, or by a 2-step method with EFS20 and EFS40. After warming, the survival of the embryos was assessed by their morphology, their ability to develop to blastocysts (or expanded blastocysts for blastocysts) in culture, or their ability to develop to term after transfer. Most (91–100%) of the embryos recovered after vitrification were morphologically normal in all developmental stages. However, the developmental ability of 1-cell embryos was quite low; exposing them to EFS40 for just 0.5min decreased the in vitro survival rate from 76 to 9%. The survival rates of 2-cell embryos and blastocysts, both in vitro and in vivo, were significantly higher with a 2-step vitrification process than with a 1-step vitrification process. Very high in vitro survival rates (94–100%) were obtained in 4- to 8-cell embryos and morulae in the 1-step method. Although survival rates in vivo of 4-cell (40%) and 8-cell (4%) embryos vitrified by the 1-step method were comparatively low, the values were similar to those obtained in non-vitrified fresh embryos. When morulae vitrified by the 1-step method were transferred to recipients, the in vivo survival rate (61%) was high, and not significantly different from that of fresh embryos (70%). These results show that rat embryos at the 2-cell to blastocyst stages can be vitrified with EFS40, and that the morula stage is the most feasible stage for embryo cryopreservation in this species.

Pregnancies derived from vitrified human zygotes

Pregnancies derived from vitrified human zygotes

O-207. Functional viability of mouse oocytes vitrified in an ethylene glycol-based solution

O-207. Functional viability of mouse oocytes vitrified in an ethylene glycol-based solution

Vitrification of Two-Cell Rat Embryos Derived from Immature HypothyroidrdwRats byin VitroFertilization in Ethylene Glycol-Based Solutions

Two-cell embryos derived from immaturerdwrats byin vitrofertilization (IVF) were vitrified in ethylene glycol-based solutions. Embryos exposed to EFS20 before being vitrified in EFS40 exhibited improved viabilityin vitro.All embryos exposed to EFS20 for 1–3 min before vitrification in EFS40 were morphologically normal. However, 2–3 min of exposure to EFS20 increased the number of embryos that developed beyond the four-cell stage. More embryos exposed to EFS20 for 2–3 min developed to morulae (63–64%) and blastocysts (34–38%) than those exposed for 1 min (35 and 10%, respectively). After transfer, 33% of embryos exposed to EFS20 for 3 min and vitrified in EFS40 developed to term compared to 29% of fresh embryos. Fifteen (47%) of live young were homozygousrdwand all of the others were heterozygous rats. The present study demonstrated that vitrification in EFS solution can be routinely used to cryopreserve rat two-cell IVF-embryos with no loss of viability.

Sugars Exert a Major Influence on the Vitrification Properties of Ethylene Glycol-Based Solutions and Have Low Toxicity to Embryos and Oocytes

A systematic approach was taken to assess the vitrification properties of ethylene glycol-based solutions supplemented with carbohydrates. Solutions were prepared by weight (gravimetrically) using ethylene glycol as the cryoprotectant, 0.9% NaCl in water, and six different sugars:d-glucose,d(−)-fructose,d-sorbitol, sucrose,d(+)-trehalose, and raffinose. Sugars were added on a molal basis (0.1, 0.5, and 1m). Characteristics of the solutions were measured during warming by differential scanning calorimetry using a cooling rate of 100°C/min and a warming rate of 10°C/min. In the absence of carbohydrates a 59 wt% EG-saline solution formed a stable glass. When EG was replaced by an equimolal concentration of glucose, fructose, or sorbitol (monosaccharides) at 0.1, 0.5, or 1.0mthere was no change in the total solute concentration at which vitrification occurred, but the glass transition (Tg) occurred at a higher temperature than in EG-saline alone. When EG was replaced by an equimolal concentration of sucrose or trehalose (disaccharides) both the Tg and the lowest total solute concentration required for vitrification became progressively higher as the molecular weight, or the ratio of sugar to EG in the solutions, increased. At the highest tested disaccharide concentration (1m) vitrification was achieved at a total solute concentration of 65 wt% (sucrose) and 67 wt% (trehalose). The polysaccharide raffinose significantly modified the vitrification properties of ethylene glycol solutions. When 0.5 or 0.1mraffinose replaced EG on an equimolal basis the glass transition point was raised more than with either the monosaccharides or the disaccharides. Raffinose allowed vitrification at a total solute concentration of 67 wt% (0.5m) and 63 wt% (0.1m). The maturation of immature mouse oocytes, and the development of embryos in media containing 5–7 mM of any sugar was comparable to controls, indicating that they are not toxic. Exposure of freshly collected GV or MII oocytes to sugar concentrations between 0.5 and 1.0 M, for up to 10 min had no significant effect on the proportion which subsequently formed two cells. We conclude that added sugars do contribute to a solutions overall vitrification properties, and their properties should be taken into consideration when vitrification solutions are being designed or modified.

Superovulation of rabbits with FSH alters in vivo development of vitrified morulae

Morulae were flushed from the oviducts and uteri of New Zealand White (NZW) rabbits superovulated with either 6 (3 d) or 8 (4 d) injections of FSH and from nonsuperovulated controls. The percentages of embryos recovered from 4 d (100%, n=8) donors was significantly higher (P<0.01) than that of 3 d (76%, n=16) and control (87%, n=22) donors. Overall, fertilization rates were significantly lower for the 3 d embryos (P<0.01). Most (86 to 90%) morulae were morphologically suitable for vitrification in an ethylene glycol-based solution. Following storage in liquid nitrogen, morulae were rapidly thawed and transferred to the uteri of pseudopregnant recipients. The total number of kits born for the 3 d, 4 d, and control groups was 40, 61 and 48, respectively. The percentage of live kits from morulae transferred was significantly lower for the 3 d (20%, n=201) than either the 4 d (36%, n=169; P<0.01) or the control (31%, n=157; P<0.05) group. The mean number of kits born/recipient for the 3 d (2.4±2.9), 4 d (4.7±3.5), and control (3.0±2.2) protocols did not differ (P>0.05). The estimated overall efficiency of producing kits based on normal morulae collected for control and 4 d groups, however, was nearly two-fold that for females given 6 FSH treatments. We conclude that the 4 d FSH superovulation regimen enhances the efficiency of rabbit reproductive biotechnology after embryo cryopreservation. These findings have important implications for rabbit colony management using embryo cryopreservation.