Effect of essential amino acids on mouse embryo viability and ammonium production

PURPOSE

To examine the effect of essential amino acids concentrations on mouse embryo development.

METHODS

Mouse embryos were cultured in medium with different concentrations of essential amino acids and development to the blastocyst stage and viability assessed. Ammonium production resulting from medium breakdown and amino acid metabolism by embryos were also assessed.

RESULTS

Reducing the essential amino acid concentration significantly increased blastocyst development and cell numbers. Lowering the essential amino acid concentration decreased ammonium production in the medium.

CONCLUSIONS

Culture media for the development of preimplantation embryos should have a reduced essential amino acid concentration to facilitate embryo development.

Altering intracellular pH disrupts development and cellular organization in preimplantation hamster embryos

In early cleavage stage hamster embryos, the inability to regulate intracellular pH (pHi) properly is associated with reduced developmental competence in vitro. The disruption of mitochondrial organization is also correlated with reduced development in vitro. To determine the relationship between pHi and the disruption of cytoplasmic organization, we examined the effects of altering pHi on hamster embryo development, mitochondrial distribution, and cytoskeletal organization. The weak base trimethylamine was used to increase pHi and was found to reduce embryo development and disrupt the perinuclear organization of mitochondria. The weak acid 5,5-dimethyl-2,4-oxazolinedione was used to decrease pH(i) and was also found to reduce development and disrupt the perinuclear organization of mitochondria. With either treatment, the microfilament organization was perturbed, but the microtubule cytoskeleton was not. However, the temporal progression of the disruption of mitochondrial distribution was more rapid in alkalinized embryos than acidified embryos, as revealed by two-photon imaging of living embryos. Additionally, the disruption of the microfilament network by the two treatments was not identical. The cytoplasmic disruptions observed were not due to acute toxicity of the compounds because embryos recovered developmentally when the treatment compounds were removed. These observations link ionic homeostasis, structural integrity and developmental competence in preimplantation hamster embryos.

The in-vitro porcine adhesion model is not predictive of the esophageal transit of risedronate tablets in humans

Mucosal damage due to esophageal adhesion of pharmaceuticals is a continued concern to both health care providers and drug manufacturers. As a result of this concern, dosage forms are now being designed to exhibit minimal esophageal adhesion. Previous researchers have used an in-vitro porcine esophageal model to determine the propensity for formulations to adhere to the esophagus as an alternative to human scintigraphy studies. This study used a porcine esophageal adhesion model similar to that used previously to determine the adhesiveness of placebo bisphosphonate formulations. Results are analogous to those obtained by previous researchers, with film-coated tablets showing greater adhesiveness than uncoated tablets. These same tablet formulations were also evaluated previously by a human scintigraphy study, and the results were exactly opposite of those obtained using the in-vitro porcine model. In the human scintigraphy study, the film-coated placebo risedronate tablet had a faster transit time than an uncoated round placebo tablet. In conclusion, the in-vitro porcine esophageal model is not predictive of esophageal transit in man and gamma scintigraphy is the preferred method to evaluate esophageal transit.

Differences in intracellular pH regulation by Na(+)/H(+) antiporter among two-cell mouse embryos derived from females of different strains

Regulation of intracellular pH (pH(i)) by two-cell-stage embryos derived from female mice of three different strains (CF-1, Balb/c, and BDF) was investigated. Embryos recovered at a slow rate from intracellular acidosis produced by a pulse of NH(4)Cl; the rate did not differ significantly among strains. Recovery was reversibly inhibited by amiloride or the absence of Na(+), implicating Na(+)/H(+) antiporter activity. The threshold pH(i) (setpoint) below which Na(+)/H(+) antiporter activity was elicited was approximately 7.15 for each strain. No recovery from induced acidosis occurred in the absence of external Na(+) in any strain, and thus embryos could be maintained in acidosis for an extended period. Upon reintroduction of Na(+), embryos derived from either CF-1 or BDF females recovered at a slow rate comparable to that measured in embryos not maintained for a period in Na(+)-free medium, but embryos derived from Balb/c females consistently recovered at a highly accelerated rate. This accelerated recovery appeared to be due, in part, to an activation of the Na(+)/H(+) antiporter in Balb/c-derived embryos, which did not occur in CF-1- or BDF-derived embryos. Thus, embryos derived from different strains of female mice differ in their control of mechanisms for pH(i) regulation.

Differential effect of hexoses on hamster embryo development in culture

The effects of glucose, fructose, and galactose on hamster embryo development in the absence of phosphate were studied in culture. One- and two-cell embryos were cultured to the blastocyst stage in HECM-9 medium without hexose or in medium with increasing concentrations of hexoses. Embryo development, cell number, and cell allocation were assessed in blastocysts. Blastocyst viability was determined by transfer to pseudopregnant recipients. Although 0.25 mM fructose increased mean cell number, low glucose concentrations had no stimulatory effect on development to blastocyst. Both galactose and 5.0 mM glucose were detrimental to embryos. Addition of 0.5 mM glucose increased implantation and fetal viability as compared with controls. Compared with 0.5 mM glucose, treatment with 0.25 mM fructose gave similar implantation and fetal viability, whereas 5.0 mM glucose tended to decrease implantation and significantly decreased fetal development. These data demonstrate that morphology is a poor indicator of embryo viability and that exposure of preimplantation embryos to glucose or fructose is important for embryo viability post-transfer. Although no difference in blastocyst viability was detected between embryos cultured with 0.25 mM fructose and those cultured with 0.5 mM glucose, increased cell numbers obtained with fructose suggest that fructose may be more appropriate than glucose for inclusion in culture medium.

Assessment of metabolism of equine morulae and blastocysts

Nutrient uptakes and metabolite production by equine morula and blastocyst stage embryos were determined by non-invasive microfluorometry. Equine morula took up equal amounts of both pyruvate and glucose. However, at the early blastocyst there was a small increase in glucose uptake and, by the expanded blastocyst stage, glucose was the predominant nutrient. Expanded blastocysts took up five times more glucose than pyruvate. Expanded blastocysts exhibited an exponential increase in glucose uptake and lactate production with respect to both diameter and surface area. As less than 50% of the glucose was accounted for by lactate production, the equine blastocyst appears to have a significant capacity to oxidize glucose. Embryos with a higher morphological grade consumed more nutrients than those with a poorer morphology. However, there was a large range in nutrient consumption within the highest grade blastocysts. This suggests that nutrient uptake may be useful as a viability marker of equine blastocysts.

Regulation of ionic homeostasis by mammalian embryos

Control and regulation of cellular homeostasis are essential for normal embryo development and maintenance of viability. By understanding the role of ionic homeostasis in normal cell development and homeostatic control by the developing embryo, it is possible to develop culture systems that minimize cellular stress and therefore maintain embryo viability. This article discusses the regulation of intracellular levels of protons (pHi), calcium, magnesium, and phosphate in mammalian embryos.

Embryo nutrition and energy metabolism and its relationship to embryo growth, differentiation, and viability

Over the past decade there has been a resurgence of interest in the culture media used in clinical in vitro fertilization. Unfortunately, during this time more confusion than consensus appears to have developed regarding the composition of these media. In order to facilitate a clearer understanding of this field, it is important to understand the role of specific medium components and how their use is regulated by the embryo. The roles of the key nutrients glucose, pyruvate, lactate, and amino acids during the preimplantation period have therefore been presented. Analysis of how the embryo regulates the utilization of such nutrients has led to a clearer understanding of the embryo's requirements during the dynamic period of preimplantation development. From such information, sequential culture media have been developed along with novel noninvasive tests of embryonic viability. It is proposed that continued studies on the human embryo will lead to further improvements in embryo culture conditions and the optimization of viability assays, culminating in the ability to transfer single embryos for the majority of, if not all patients.

Vitrification of mouse oocytes using a nylon loop

Cryopreservation of mouse oocytes was improved by the use of ultra-rapid vitrification using a nylon loop of 0.5 mm diameter. Oocytes that were vitrified using the loop survived at high rates and were fertilized following a small hole being made in the zona pellucida (69.8%) and developed to the blastocyst stage in culture (67.4%) at similar rates to that of oocytes that were not cryopreserved. Blastocysts resulting from oocytes vitrified using the nylon loop had similar development of the inner cell mass and trophectoderm as blastocysts from non-cryopreserved oocytes. In contrast, oocytes that were cryopreserved using a slow-freezing protocol where most of the Na+ is replaced with choline had lower rates of fertilization (39.5%), reduced development to the blastocyst stage (25.7%), and blastocysts had reduced development of the inner cell mass. Blastocysts derived from oocytes that were vitrified with the nylon loop were able to implant (88.0%) and develop into fetuses (56.5%) at significantly higher rates compared to blastocysts derived from oocytes that were slow-frozen (52.4 and 26.2%, respectively). Vitrification of mouse oocytes using the nylon loop results in the retention of viability of the oocytes and subsequent embryos.

Substrate utilization in porcine embryos cultured in NCSU23 and G1.2/G2.2 sequential culture media

Embryo metabolism is an indicator of viability and, therefore, efficiency of the culture medium. Currently, little is known regarding porcine embryo metabolism. The objective of our study was to evaluate glucose and pyruvate uptake and lactate production in porcine embryos cultured in two different media systems. Oocytes were matured and fertilized according to standard protocols. Embryos were allocated randomly into two culture treatments, NCSU23 medium or G1.2/G2.2 sequential culture media 6-8 h post-insemination (hpi). Embryo substrate utilization was measured at the two-cell (24-30 hpi), 8-cell (80 hpi), morula (120 hpi), and blastocyst (144 hpi) stages using ultramicrofluorimetry. Glucose uptake was higher (P < 0.05) in two-cell embryos cultured in G1.2 than in NCSU23 medium (4.54 +/- 0.71, 2.16 +/- 0.87 pmol/embryo/h, respectively). Embryos cultured in G1.2/G2.2 produced significantly more lactate than those in NCSU23 at the eight-cell stage (9.41 +/- 0.71, 4.42 +/- 0.95 pmol/embryo/hr, respectively) as well as the morula stage (11.03 +/- 2.31, 6.29 +/- 0.77 pmol/embryo/hr, respectively). Pyruvate uptake was higher (P < 0.05) in morula cultured in G1.2/G2.2 versus NCSU23 (22.59 +/- 3.92, 11.29 +/- 1.57 pmol/embryo/h, respectively). Lactate production was greater (P < 0.05) in blastocysts cultured in G1.2/G2.2 (38.13 +/- 15.94 pmol/embryo/h) than blastocysts cultured in NCSU23 (8.46 +/- 2.38 pmol/embryo/h). Pyruvate uptake was also greater in blastocysts cultured in G1.2/G2.2 (24.3 +/- 11.04) than those in NCSU23 (11.30 +/- 2.70). When cultured in NCSU23 medium, two- and eight-cell embryos utilized less glucose than morulae and blastocysts, and two-cell embryos produced less lactate than blastocysts (P < 0.05). In G1.2/G2.2 media, two-cells took up less pyruvate than morulae or blastocysts, while blastocysts produced more lactate and utilized more glucose than two-cell, eight-cell and morula stage embryos (P < 0.05). As in other species, glycolysis appears to be the primary metabolic pathway in post-compaction stage porcine embryos. Culture medium composition affects not only substrate uptake, but also metabolic pathways by which these substrates are utilized in porcine embryos at several developmental stages.

A cross-link breaker has sustained effects on arterial and ventricular properties in older rhesus monkeys

Nonenzymatic glycosylation and cross-linking of proteins by glucose contributes to an age-associated increase in vascular and myocardial stiffness. Some recently sythesized thiazolium compounds selectively break these protein cross-links, reducing collagen stiffness. We investigated the effects of 3-phenacyl-4,5-dimethylthiazolium chloride (ALT-711) on arterial and left ventricular (LV) properties and their coupling in old, healthy, nondiabetic Macaca mulatta primates (age 21 +/- 3.6 years). Serial measurements of arterial stiffness indices [i.e., aortic pulse wave velocity (PWV) and augmentation (AGI) of carotid arterial pressure waveform] as well as echocardiographic determinations of LV structure and function were made before and for 39 weeks after 11 intramuscular injections of ALT-711 at 1.0 mg/kg body weight every other day. Heart rate, brachial blood pressure, and body weight were unchanged by the drug. PWV and AGI decreased to a nadir at 6 weeks [PWV to 74.2 +/- 4.4% of baseline (B), P = 0.007; AGI to 41 +/- 7.3% of B, P = 0.046], and thereafter gradually returned to baseline. Concomitant increases in LV end diastolic diameter to 116.7 +/- 2.7% of B, P = 0.02; stroke volume index (SV(index)) to 173.1 +/- 40.1% of B, P = 0.01; and systolic fractional shortening to 180 +/- 29.7% of B, P = 0.01 occurred after drug treatment. The LV end systolic pressure/SV(index), an estimate of total LV vascular load, decreased to 60 +/- 12.1% of B (P = 0.02). The LV end systolic diameter/SV(index), an estimate of arterio-ventricular coupling, was improved (decreased to 54.3 +/- 11% of B, P < 0.002). Thus, in healthy older primates without diabetes, ALT-711 improved both arterial and ventricular function and optimized ventriculo-vascular coupling. This previously unidentified cross-link breaker may be an effective pharmacological therapy to improve impaired cardiovascular function that occurs in the context of heart failure associated with aging, diabetes, or hypertension, conditions in which arterial and ventricular stiffness are increased.

Using the gross motor function measure to evaluate motor development in children with Down syndrome

The purpose of this article is to describe our clinical experiences in using the Gross Motor Function Measure (GMFM) to evaluate motor development in children with Down syndrome and to provide strategies we found helpful in enhancing a child's adherence to standardized testing. The issues discussed are: (1) strategies for test administration; (2) modifications in administration and scoring; (3) reliability of the GMFM using the modified administration and scoring procedures; and (4) applications of the GMFM for clinical practice. The strategies and recommendations address the particular characteristics of children with Down syndrome and allow for their progress to be monitored relative to other children with Down syndrome rather than to children without motor delays. Future studies validating the use of specific goal areas for the administration and scoring of the GMFM for children with Down syndrome are recommended.

Mechanisms for managing cellular and homeostatic stress in vitro

The ability to maintain embryo development in culture depends upon the ability of the embryo to maintain cellular homeostasis. Disruptions in the ability to regulate cellular homeostasis such as pH, calcium levels and osmotic pressure result in perturbed development and a reduced ability to establish and maintain a pregnancy following transfer. Therefore, it is important that in vitro conditions are designed to minimize stress on the embryo and maximize the ability of the embryo to maintain cellular homeostasis. While embryos do exhibit a degree of plasticity and can adapt to their environment, this requires expenditures of extra energy which negatively impacts viability. Therefore, reducing stress by taking into account the physiology of the embryo is essential for the maintenance of developmental competence in vitro.

Culture and transfer of viable blastocysts: a feasible proposition for human IVF

In spite of the numerous advances in the field of human assisted reproductive technologies (ART) over the past 20 years, a rate-limiting factor in the overall efficiency of the procedure (the implantation rate) has remained at 10-30%. The development of sequential media has led to the ability to culture routinely the human embryo to the viable blastocyst stage. Transfer of such blastocysts has resulted in a significant increase in implantation rates. Increases in implantation rates following blastocyst transfer have been reported for specific groups of patients culminating in the elimination of high order multiple gestations. Of greater significance, however, is that the introduction of blastocyst transfer to all patients entering infertility clinics is associated with an overall increase in implantation and pregnancy rates. Blastocysts derived from the use of sequential media are readily cryopreserved and produce high implantation rates after transfer. Using a model to account for both total embryo utilization per cycle (transferred plus cryopreserved) and implantation rate, it has been calculated that extended embryo culture and blastocyst transfer is approximately 20% more efficient than the transfer of cleavage stage embryos on day 3. Furthermore, as the score of the blastocysts obtained using sequential media is directly related to implantation and pregnancy rates, it is possible to determine which patients should be offered a single blastocyst transfer, thereby addressing the issue of twins conceived through ART.

EDTA stimulates cleavage stage bovine embryo development in culture but inhibits blastocyst development and differentiation

Culture of bovine zygotes in medium SOFaa supplemented with 100 microM EDTA significantly increased cleavage rates during the first 72 hr of development compared to development in SOFaa. However, continued culture in the presence of EDTA for a further 72 hr (total of 6 days of culture) resulted in significantly reduced development to the morulae/blastocyst and blastocyst stages compared to culture without EDTA. Highest rates of development to the morulae/blastocyst stage (56.5%) and to the blastocyst stage (43.2%) were achieved when zygotes were cultured for 72 hr with EDTA before transfer to medium SOFaa without EDTA. Resultant blastocysts also had significantly increased blastocyst cell number and ICM cell number compared to those cultured without EDTA in the first 72 hr. EDTA was shown to inhibit glycolytic activity of the cleavage stage embryo, thereby preventing the premature stimulation of glycolysis and enhancing development. However, EDTA should not be used for the later stage embryo as the inhibition of glycolysis reduces energy production at the blastocyst stage and significantly inhibits inner cell mass development.

Blastocyst score affects implantation and pregnancy outcome: towards a single blastocyst transfer

OBJECTIVE

To determine the relationship between blastocyst score and pregnancy outcome.

DESIGN

Retrospective review of blastocyst transfer in an IVF clinic.

SETTING

Private assisted reproductive technology unit.

PATIENT(S)

107 patients undergoing blastocyst culture and transfer of two embryos.

INTERVENTION(S)

Culture of all pronucleate embryos in sequential media to the blastocyst stage (day 5), followed by transfer of two blastocysts.

MAIN OUTCOME MEASURE(S)

Implantation rates, pregnancy rates, and twinning were analyzed.

RESULT(S)

When a patient received two top-scoring blastocysts (64% of patients), implantation and pregnancy rates were 70% and 87%, respectively. The twinning rate in this group was 61%. When only one top-quality blastocyst was available for transfer (21% of patients), the implantation and pregnancy rates were 50% and 70%. The twinning rate for this group was 50%. In contrast, when only low-scoring blastocysts were available for transfer (15% of patients), implantation and pregnancy rates were 28% and 44%, and the twinning rate was 29%. No monozygotic twins were observed in this group of patients.

CONCLUSION(S)

The ability to transfer one high-scoring blastocyst should lead to pregnancy rates greater than 60%, without the complication of twins.

Evaluation of botulinum toxin A therapy in children with adductor spasm by gross motor function measure

Intramuscular injection of botulinum neurotoxin A is a relatively new method for treating spastic movement disorders in children. One major goal of any therapy for patients with movement disorders is to improve gross motor function. In this study, 18 patients with adductor spasm were treated with botulinum neurotoxin A. Treatment effect was determined with the Gross Motor Function Measure, a standardized, validated instrument designed to assist in assessment of gross motor function. Spastic muscle hyperactivity and joint mobility were evaluated by the modified Ashworth Scale and by range of motion, respectively. Compared to pretreatment values, significant improvement in gross motor function (P < .010), decrease in the modified Ashworth Scale, and increase in the range of motion (P < .010) were achieved. Patients with moderate impairment of gross motor function (classed at level III and level IV in the Gross Motor Function Classification System) benefited most from treatment. In patients with severe handicap (level V), only one of five treated patients showed improvement in gross motor function. Nevertheless, all patients in this subgroup benefited from improved ease in hygienic care. In conclusion, we have demonstrated that for most children with moderate functional impairment, the Gross Motor Function Measure is a useful instrument for objective documentation of improvements of gross motor function following treatment with botulinum neurotoxin A.

A single medium supports development of bovine embryos throughout maturation, fertilization and culture

Oocytes and embryos are typically exposed sequentially to varying culture media in standard in-vitro protocols. Expenditures of energy may be required following each medium change to adjust to the changing environment. Therefore, a single base medium was evaluated for its ability to support in-vitro maturation, fertilization and pre-implantation development (IVM/F/C) of bovine oocytes and embryos. Four treatments were examined: a standard maturation [tissue culture medium (TCM) 199 with bovine calf serum (BCS)], fertilization (modified Tyrode's medium with albumin, lactate and pyruvate) and culture (hamster embryo culture medium/TCM with BCS) system (control) and three synthetic oviductal fluid (SOF) treatments; maturation in SOF with bovine serum albumin (SOFBSA), SOF with bovine calf serum (SOFBCS) or the control maturation medium (TCM199 with BCS; SOF199), followed by fertilization and culture in SOF medium. The percentage of total inseminated oocytes successfully developing to the morula and blastocyst stage did not differ (P > 0. 05) between treatments (control, 30.5 +/- 3.5; SOFBSA, 24.6 +/- 3.2; SOFBCS, 22.4 +/- 4.7; SOF199, 27.3 +/- 3.2). Embryos cultured in SOFBCS (92.1 +/- 6.4) had significantly higher cell numbers (P < 0. 05) than those cultured in control (74.8 +/- 4.8) and SOFBSA (71.6 +/- 6.6) but not SOF199 (81.2 +/- 6.8). In conclusion, a single medium can be used successfully throughout maturation, fertilization and pre-implantation embryo development. Moreover, inclusion of serum during maturation in the single medium system resulted in significantly greater cell numbers, possibly reflecting increased quality of the embryos produced.

Cryopreservation reduces the ability of hamster 2-cell embryos to regulate intracellular pH

Vitrification of hamster 2-cell embryos impairs the activity of both the Na(+)/H(+) antiporter and HCO(3)(-)/Cl(-) exchanger; the two transport proteins responsible for the regulation of intracellular pH (pHi). The activities of both the Na(+)/H(+) antiporter and HCO(3)(-)/Cl(-) exchanger were significantly reduced at 4 h following warming compared to freshly collected embryos. Normal levels of activity of both transporters were not restored until 6 h after warming. Thus, cryopreservation of cleavage stage hamster embryos has a detrimental effect on their ability to maintain intracellular ionic homeostasis. Impairment of these pHi regulatory proteins resulted in the pHi of embryos being significantly elevated from the control values of 1.2 to 7.35 for approximately 4 h after warming. In addition, an elevated pHi value significantly impaired oxidative metabolism. Therefore, the loss in developmental competence of embryos following cryopreservation may in part be explained by a reduced ability to regulate intracellular pH that results in perturbations in metabolism and disruption of energy production.

Ondansetron versus placebo for prophylaxis of nausea and vomiting in patients undergoing ambulatory laparoscopic cholecystectomy

BACKGROUND

Postoperative nausea and vomiting is a common problem in patients undergoing laparoscopic cholecystectomy (LC). The purpose of this study was to evaluate the efficacy of ondansetron given at the induction of anesthesia in patients scheduled for ambulatory LC.

METHODS

A total of 84 patients undergoing ambulatory LC were enrolled in a randomized, prospective, double-blinded study in which the subjects received either placebo or 4 mg ondansetron intravenously at induction of anesthesia. A nausea scoring system was employed utilizing a 5-point linear scale, with 1 point given for no nausea and a maximum of 5 points for an episode of emesis. Each patient received a total of four scores postoperatively.

RESULTS

The patients receiving placebo had significantly more episodes of nausea (53 versus 32; P <0.009) and emesis (11 versus 2; P <0.02), higher mean total nausea scores (7.2 versus 5.4; P <0.006), and need for additional postoperative antiemetics (23 versus 14; P <0.05) than those receiving ondansetron.

CONCLUSIONS

In patients undergoing ambulatory laparoscopic cholecystectomy, ondansetron at induction was highly effective in decreasing postoperative nausea and vomiting and should become the standard.

Lactate regulates pyruvate uptake and metabolism in the preimplantation mouse embryo

This study was an investigation of the interaction of lactate on pyruvate and glucose metabolism in the early mouse embryo. Pyruvate uptake and metabolism by mouse embryos were significantly affected by increasing the lactate concentration in the culture medium. In contrast, glucose uptake was not affected by lactate in the culture medium. At the zygote stage, the percentage of pyruvate taken up and oxidized was significantly reduced in the presence of increasing lactate, while at the blastocyst stage, increasing the lactate concentration increased the percentage of pyruvate oxidized. Lactate oxidation was determined to be 3-fold higher (when lactate was present at 20 mM) at the blastocyst stage compared to the zygote. Analysis of the kinetics of lactate dehydrogenase (LDH) determined that while the V(max) of LDH was higher at the zygote stage, the K(m) of LDH was identical for both stages of development, confirming that the LDH isozyme was the same. Furthermore, the activity of LDH isolated from both stages was reduced by 40% in the presence of 20 mM lactate. The observed differences in lactate metabolism between the zygote and blastocyst must therefore be attributed to in situ regulation of LDH. Activity of isolated LDH was found to be affected by nicotinamide adenine dinucleotide(+) (NAD(+)) concentration. In the presence of increasing concentrations of lactate, zygotes exhibited an increase in autofluorescence consistent with a depletion of NAD(+) in the cytosol. No increase was observed for later-stage embryos. Therefore it is proposed that the differences in pyruvate and lactate metabolism at the different stages of development are due to differences in the in situ regulation of LDH by cytosolic redox potential.

Vitrification of mouse and human blastocysts using a novel cryoloop container-less technique

OBJECTIVE

To vitrify mouse and human blastocysts with use of the cryoloop procedure and to assess subsequent development.

DESIGN

Controlled study of vitrification of mouse and human blastocysts.

SETTING

Research department of a private assisted reproductive technology unit.

PATIENT(S)

Blastocysts that were not suitable to be frozen were donated from patients.

INTERVENTION(S)

Culture of pronucleate embryos in sequential media to the blastocyst stage.

MAIN OUTCOME MEASURE(S)

Survival of the vitrification procedure was assessed by reexpansion, hatching, and outgrowth in culture. In addition, the viability of mouse blastocysts was assessed after transfer to pseudopregnant recipients.

RESULT(S)

Vitrification of mouse blastocysts did not affect the ability to reexpand, hatch, or outgrow in culture. Furthermore, implantation rates and fetal development were equivalent for nonfrozen and vitrified blastocysts. Vitrified human blastocysts were able to hatch and outgrow in culture at rates similar to nonfrozen controls.

CONCLUSION(S)

Cryoloop vitrification was able to cryopreserve mouse and human blastocysts without any reduction in the ability to reexpand and hatch in culture. Furthermore, viability was not reduced by the cryoloop vitrification of mouse blastocysts.