Evaluation of human fetal cord sera, Ham's F-10 medium, and in vitro culture materials with a mouse in vivo fertilization system

Quality Management Issues in the Assisted Reproduction Laboratory

In the United States, the Clinical Laboratory Improvement Act (CLIA) of 1988 describes requirements and guidelines for implementing a quality control/quality assurance (QC/QA) program for moderate and high complexity laboratories. These requirements and guidelines apply to Assisted Reproductive Technology (ART) laboratories as well. The general topic of QC and QA as it pertains to in vitro fertilization (IVF) and embryo transfer (ET) is extensively reviewed. This review summarizes many of the QC and QA events that contribute to the advancement of knowledge in this biotechnological field. These events include control of the culture environment inside and outside of the incubator, as well as factors that affect culture media. This review also discusses, in considerable detail, the QC and the QA that pertain to equipment used within the laboratory and how to control for potential contaminants, which reside within the laboratory. This review provides evidence to indicate the need for laboratory personnel to monitor quality improvement issues on a continuous basis. Personnel must be willing to change as improvements in technology occur in order to meet the ever-evolving demands of a more difficult patient population. Suggestions for meeting these demands are offered.

Updating quality control assays in the assisted reproductive technologies laboratory with a cryopreserved hamster oocyte DNA cytogenotoxic assay

PURPOSE

Despite advances in assisted reproduction, there is no progress in quality control bioassays. The objectives were to develop a comet assay to measure DNA fragmentation in thawed cryopreserved oocytes and compare this assay with one-cell mouse embryo bioassay.

METHODS

Thawed hamster oocytes from a commercial source were incubated in culture media with either 0-, 50-, or 100-microM hydrogen peroxide, or, in media exposed to different contact materials and unknown proficiency analytes. Incubation time was 1.5 h at 37 degrees C. The oocytes were dried, fixed, stained with acridine orange, embedded in a mini-agarose layer and electrophoresis was carried out. Fluorescent images were analyzed. The results were compared with standard one-cell mouse assay data.

RESULTS

The 100-microM hydrogen peroxide treatment caused greatest DNA fragmentation in the hamster oocytes at Hours 1 and 2. A dose response was observed. Intraassay coefficient of variation was 5.7%. Only one of the five materials tested passed both assays. The data for the unknown proficiency analytes were similar for both assays.

CONCLUSIONS

The oocyte comet assay demonstrated DNA fragmentation in the presence of toxic substances. The detection of toxicity in two materials that passed the mouse bioassay suggested increased sensitivity in the new assay. The oocyte comet assay and the mouse bioassay results matched in the proficiency test. However, more studies are still needed to determine optimal sensitivity.

In vitro stimulation of cumulus-cell expansion by human cord serum in mouse oocyte-cumulus complexes

PURPOSE

The aim of this study was to test whether human cord serum (HCS) containing gonadotropins has an effect on the expansion of oocyte-cumulus complexes (OCCs).

METHODS

The concentration of follicle stimulating hormone (FSH) and luteinizing hormone (LH) was measured in HCS by radioimmunoassay (RIA). After short-term culture (4 hr) with or without OCCs, medium containing 0.4% bovine serum albumin (BSA) as control or 10% HCS was collected and analyzed for its concentration of estradiol, progesterone, and testosterone.

RESULTS

The FSH concentration was at the basal level, but the LH level was as high as 142.4 mIU/ml in both natured and denatured serum. Undetectable levels of steroids were observed in control media with or without OCCs. In contrast, a moderate amount of steroid hormones was detected in culture medium containing HCS. OCCs secreted a minute amount of steroid hormones in response to HCS. Similar patterns of cumulus expansion were observable by treatment with HCS, human chorionic gonadotropin (hCG), or HCS plus hCG after 4, 8, or 22 hr of culture. However, no cumulus expansion was observed in controls.

CONCLUSION

These results suggest that LH in HCS induces cumulus expansion but does not affect the secretion of steroid hormones by OCCs during culture.

Assessment of the quality of frozen serum by spectrophotometric analysis and sperm bioassay

Serum is an integral part of media used for in vitro fertilization (IVF) and andrology work. Previous studies showed that the IVF results could benefit if sera were screened for deleterious effects before use. Such screening is impractical when fresh sera are used but may be feasible if the serum is frozen prior to use. This study assessed the impact of freezing on the quality of serum. A total of 158 serum samples, prepared in a university-based andrology-IVF center, were included in the study. The frozen sera were thawed in batches to be used in a series of laboratory experiments. Serum quality was evaluated by spectrophotometric analysis and sperm bioassay under several defined conditions: fresh, frozen, pre- and postfiltration, pre- and postcentrifugation, and the patients' fertility condition. Although all sera were filtered through 0.22-micron filter, more than 10% frozen sera required 0.4- or a combination of 0.8- and 0.4-micron filters before they could be passed through the 0.22-micron filter. Frozen sera that were directly filtrable with a 0.22-micron filter lost 13% turbidity upon filtration. The turbidity of the frozen sera were higher compared to fresh ones as revealed by optical density (OD) and relative light scattering (RLS) spectrophotometry. The freeze/storage-induced spectrophotometric changes did not correlate with the storage time. The centrifugation caused precipitation of sera components. The rate of precipitation of the serum components correlated with the duration of freezing. Spectrophotometric analysis and sperm bioassay did not differentiate the sera of pregnancy-positive and pregnancy-negative subjects. The sperm bioassay failed to detect any biological impact of freezing-induced spectrophotometric changes in the sera, suggesting that the freezing-induced changes did not significantly diminish the serum's capability of supplementing the culture media.

Evaluation of serum-associated embryotoxicity in women with reproductive disorders

PURPOSE

Our purpose was to determine whether some cases of infertility may be due to serological factors inhibiting development of the embryo.

METHOD

We examined the effect of infertile women's sera on the expansion, attachment, and spreading of mouse blastocysts in culture. Cell marker expression was also assayed by an indirect immunofluorescence technique. Serum samples from 75 infertile women were compared to the effect of 24 control AB sera.

RESULTS

After 72 hr, blastocyst spreading was significantly different depending on whether cultured in sera from women with unexplained infertility, anovulatory infertility, diethylstilbesterol exposure or controls. Neither sera from women with mechanical infertility (14) nor sera from women with endometriosis (8) affected blastocyst growth in culture.

CONCLUSIONS

Inhibitory sera were capable of reducing cytokeratin expression but had no effect on placental alkaline phosphatase or concanavalin A expression by blastocyst cells. It can be inferred that the inhibitory effect of sera from women with certain types of infertility might be due to damage to the cytoskeleton. This in vitro assay may predict the success or failure of IVF.

Effects of human serum supplementation on fertilization and development of mouse embryos

Serum is generally used as a protein supplement in culture media for human in vitro fertilization (IVF). To determine the effects of serum supplementation on the development of preimplantation embryos, one-cell and two-cell mouse embryos fertilized in vitro and in vivo were cultured in BWW medium supplemented with preovulatory patient serum (PS), human fetal cord serum (HCS), or bovine serum albumin (BSA). The rates of fertilization and development of embryos fertilized in vitro and in vivo were suppressed when the embryos were cultured with PS or HCS as compared with BSA. In the medium supplemented with HCS, growth of in vitro fertilized embryos was retarded at an earlier embryonic stage than was the case with embryos fertilized in vivo. These results suggest that the in vitro fertilized embryo culture model is more sensitive to culture conditions than is the in vivo fertilized embryo culture model. Incorporations of [3H]uridine and [3H]leucine were measured using embryos that developed to the blastocyst stage in a medium supplemented with HCS or BSA. Blastocysts cultured with HCS showed significantly higher incorporations of [3H]uridine and [3H]leucine than those cultured with BSA. While serum supplementation in culture media has adverse effects on embryo cleavage, it augments synthesis of RNA and protein.

A correlation of the outcome of clinical in vitro fertilization with the inositol content and embryotrophic properties of human serum

PURPOSE

This study was designed to investigate whether the level of myo-inositol (MI) in human serum is critical for embryotrophic activity.

METHODS

The embryotrophic properties of human serum were evaluated by the development of postimplantation mouse embryos [in vitro assay of Tam et al. (Fertil Steril 48:834-839, 1987)]. An enzymatic spectrophotometric method using myo-inositol dehydrogenase was used for determination of serum MI. The level of MI detected in serum was compared with the embryotrophic properties and the pregnancy outcome. The effect of MI on the embryotrophic activity of human serum was studied by supplementing the suboptimal serum samples that were unsupportive of embryo growth with extra MI.

RESULTS

Serum obtained from patients having successful IVF pregnancies generally supported better development of postimplantation mouse embryos and contained higher levels of inositol, particularly if the serum sample was collected during the IVF treatment cycle. Serum samples obtained from patients with aborted pregnancies, though supporting mouse embryo development, contained significantly lower concentrations of inositol. An improvement of the embryotrophic properties with exogenous inositol supplement was achieved in some but not all of the suboptimal serum samples studied.

CONCLUSIONS

It is possible that other factors in addition to inositol are crucial in promoting better embryonic development.

Measurement of uptake and incorporation of nucleic acid precursors by preimplantation mouse embryos after development in vivo and in vitro

PURPOSE

To assay DNA and RNA synthesis by developing mouse embryos in vitro and in vivo, we measured the uptake and incorporation of 3H-thymidine and 3H-uridine by morulae and blastocysts. We also evaluated the effect of adding EDTA to the culture medium on the uptake and incorporation of nucleic acid precursors by blastocysts.

RESULTS

Thymidine and uridine incorporation increased after morulae developed into early blastocysts both in vitro and in vivo. However, the rates of uptake and incorporation were significantly lower by embryos grown in vitro than by those grown in vivo. The ratios of incorporation to total uptake were similar in embryos grown in vitro and in vivo. EDTA (100 microM) added to the culture medium significantly increased the incorporation of uridine into RNA by blastocysts grown in vitro (P < 0.01) but did not increase the total uptake of uridine.

CONCLUSION

These observations showed that both DNA and RNA synthesis increased during the early development of preimplantation embryos and that those activities were reduced in embryos undergoing development in vitro. The results also suggested that through the mechanism of EDTA effect in embryo culture remains unknown, it appeared to reduce the retardation of RNA synthesis by embryos cultured in vitro through a selective stimulation of uridine incorporation.

Stimulation of folliculogenesis in domestic cats with human FSH and LH

Folliculogenesis in response to exogenous stimulation by human urinary follicle stimulating hormone (huFSH) and human menopausal gonadotropin (hMG) was evaluated in the domestic queen (Felis catus). The role of LH and/or FSH in folliculogenesis was examined by measuring concentrations of estradiol 17beta (E(2)) and progesterone (P) in the serum. Additionally, changes in the number and size of follicles from before the administration of exogenous hormones to surgical oocyte collection were monitored. Findings indicated that in queens receiving huFSH or hMG followed by human chorionic gonadotropin (hCG) to induce ovulation, the numbers of follicles from 1 to 3 mm increase with statistical significance (P<0.005) from before the initiation of treatment to surgical collection of oocytes. Although E(2) concentrations in cats receiving hMG increased above baseline by the third exogenous hormone injection, mean E(2) concentrations did not increase in the groups that received both huFSH and hCG, or hCG only, until after the administration of hCG. This suggests that the exogenous administration of LH contained in both hMG and hCG was necessary for E(2) to rise to levels associated with estrus.

Fucoidin inhibits the zona pellucida-induced acrosome reaction in human spermatozoa

We recently reported that fucoidin (a polymer of predominantly sulfated L-fucose) significantly inhibits tight binding of human sperm to the human zona pellucida in vitro and that several oligosaccharides obtained after acid hydrolysis possess sperm-zona pellucida binding inhibitory activity equal to the original fucoidin. This inhibition may be specific to sperm-zona interactions or may be the consequence of the interruption of capacitation, a series of biochemical and physiological events leading to final sperm maturation, that must occur for successful fertilization. Completion of capacitation is most often determined by assessing two end-points of the process: acquisition of hyperactivated motility and ability to complete the acrosome reaction. Here, we examined the effects of fucoidin on these two end-points of capacitation in vitro. Fucoidin did not affect the proportion of sperm with hyperstimulated motility. Neither did fucoidin cause an increase in sperm that had spontaneously acrosome-reacted at 4.5 hours compared to controls as evaluated by indirect immunofluorescence using the acrosomal marker, monoclonal antibody, T-6. Comparable percentages of sperm had completed the acrosome reaction when exogenously stimulated by calcium ionophore A23187 with and without the addition of fucoidin. However, in the presence of fucoidin, stimulation of the acrosome reaction by acid solubilized human zonae pellucidae was significantly inhibited. These data indicate that fucoidin does not impede the normal progression of capacitation. These results provide strong evidence to support the hypothesis is that the inhibitory effect of fucoidin is at the level of the sperm membrane since inhibition can be bypassed by increasing intracellular calcium directly with a calcium ionophore.

Reduction of embryotoxicity by protein in embryo culture media

Experiments tested the hypothesis that one role of protein in embryo culture media is protection of embryos against potentially embryotoxic substances in the media. Mouse embryos were cultured in modified Krebs-Ringer bicarbonate medium and in modified Tyrode's medium, aliquots of which were supplemented with 4 mg/ml of the protein bovine serum albumin (BSA), while other aliquots were left protein free. The media were prepared using water samples that differed in purity, as reflected by differences in conductivity, with tap water being least pure (and considered to have the greatest potential for being embryotoxic) and water that had been purified by reverse osmosis, Milli-Q filtration, and triple distillation being most pure. Embryos were placed in the media while in the two-cell stage of development and their development was assessed after 24, 48, and 72 hr of culture. Rate of embryo development in BSA-supplemented media was greater than that in protein-free media only when the media were prepared with the least purified water samples. Because these water samples would have contained substances not contained in media prepared with purer water, or would have contained the substances in higher concentration, the data supported the hypothesis that protein can protect embryos during culture by negating effects of embryotoxic substances in the media.

Comparison of the hamster sperm motility assay to the mouse one-cell and two-cell embryo bioassays as quality control tests for in vitro fertilization

The hamster sperm motility assay, mouse one-cell embryo, and mouse two-cell embryo bioassays were used to test modified Tyrode's solution and modified Ham's F-10 (Gibco, Grand Island, NY) medium prepared in tap water versus ultrapure water. Factors influencing the ability of each assay to discriminate water quality were evaluated to characterize these assays for quality control use in the in vitro fertilization laboratory. The hamster sperm motility assay reproducibly detected differences in treatment without significant interanimal, interanalyst, or interassay variation. Interanalyst and interanimal variation significantly affected the ability to detect treatment differences using the mouse bioassays. Sample sizes needed to predict clinically significant treatment effects were calculated using varying assay conditions. Ham's F-10 medium can be tested with the hamster sperm motility assay.

Preimplantation murine embryos are more resistant than human embryos to bacterial endotoxins

Bacterial endotoxins have been correlated with increased fragmentation of early cleavage-stage human embryos and decreased pregnancy rates in human in vitro fertilization programs. The purpose of the present study was to test the direct effects of increasing concentrations of endotoxins on in vitro fertilization and development of mouse embryos to the blastocyst stage. Sexually mature B6D2F1 female mice were superovulated and oocytecumulus complexes were collected from the oviducts and randomized into control and treatment groups. Oocytes (n = 867) were inseminated with capacitated sperm. Treatments included Ham's F-10 supplemented with 3 mg/ml bovine serum albumin and increasing amounts of endotoxin (0.35, 0.64, 0.92, 1.5, 2.08, 3.21, 6.07, and 11.79 ng/ml). Percentage cleavage, percentage fragmentation at the four-cell stage, and percentage expanded blastocyst formation (of cleaved embryos) were evaluated. Statistically significant decreases in cleavage at 6.07 ng/ml (P less than 0.05) and blastocyst formation at 11.79 ng/ml (P less than 0.05) of endotoxin were observed. Fragmentation at the four-cell stage was significantly increased at 3.21 ng/ml (P less than 0.05) of endotoxin. We conclude that the levels of endotoxin necessary to decrease murine preimplantation development significantly is higher than that reported for human embryos.

Monozygous double inner cell masses in mouse blastocysts following fertilization in vitro and in vivo

The incidence of human identical twins after in vitro fertilization and embryo transfer (IVF-ET) is estimated to be higher than the commonly accepted incidence after conception in vivo. This paper reports that 8 mouse blastocysts which had double inner cell masses in 261 blastocysts (3.1%) were identified after fertilization in vitro and they developed into trophoblastic outgrowth formation with two inner cell masses. In contrast, only 3 monozygous double inner cell masses were observed in 526 blastocysts (0.6%) which were fertilized in vivo and cultured from the two-cell stage in vitro. It is therefore possible that fertilization in vitro predisposes to monozygous twinning.

Evaluation of a synthetic serum substitute to replace fetal cord serum for human oocyte fertilization and embryo growth in vitro

A comparison was made between a serum substitute. UltroSer G (Gibco, Ghent, Belgium) (2%) (medium B) and 10% human fetal cord serum (medium A), as regards their ability to support 1-cell and 2-cell mice embryo development in vitro. Sixty percent and 56% of the 1-cell embryos reached the expanded blastocyst stage when cultured in media A and B, respectively. Eighty-four percent and 88% of 2-cell embryos reached the expanded blastocyst stage when cultured in media A and B, respectively. A prospective randomized study was then performed to evaluate this synthetic serum substitute in human in vitro fertilization. Among 141 ovum pick-up (OPU), oocytes retrieved in 74 cases were processed in medium A and oocytes retrieved in 67 others in medium B. In media A and B, the fertilization rate was 67% and 44.3% respectively, and the pregnancy rate/OPU 23% and 9%, respectively. The pregnancy rate/transfer was 28.8% and 12.2% respectively, and the implantation rate/transferred embryo 9.5% and 4.2%. In the human sperm survival assay, the vitality and residual motility after 24 hours of incubation were significantly lower in medium B. In conclusion, UltroSer G successfully sustained the development in vitro of mouse embyros. However in human, it reduced sperm survival, oocyte fertilization, and embryo viability.

Potential risk of light and room temperature exposure to preimplantation embryos

Adverse effects of simultaneous exposure to visible light and room temperature were investigated in rabbit early cleavage stages and morulae. Routine laboratory conditions were mimicked as close as possible. Embryonic development was assessed by cell proliferation via incorporation of tritiated thymidine, by gross morphology, and by electron microscopy. Damage was detectable in both stages at 1-hour exposure by statistically significant impaired cell proliferation. Compared with single exposure to each individual stressor, combined exposure to light and room temperature amplified detrimental effects. Ultrastructural analysis of light-exposed cleavage stages revealed no indication of cell injury at 4-hour exposure. Gross morphology proved to be too inaccurate to evaluate damage imposed by exposure toward both physical factors investigated.

Variables affecting toxicity of human sera in mouse embryo cultures

It has been reported that sera from women with reproductive disorders can inhibit mouse embryo development. While performing tests on this subject in our laboratory, two unexpected variables were identified that can influence the effect of human serum on mouse embryo cultures. In a standard embryo culture system in which heat-inactivated sera (10% final concentration) were added to two-cell mouse embryos and percentage blastocyst development was scored after 4 days, sera that had been collected into standard clinical Monoject blood collection red-stopper tubes were significantly more embryotoxic than sera collected from the same subjects into 15-ml Falcon centrifuge tubes (P less than 0.005). Furthermore, we observed that sera from laboratory personnel that worked with mice often inhibited mouse embryo development. To study this effect further, sera were collected from five fertile individuals who were routinely exposed to mice and from fertile women with no previous exposure to rodents. Sera from the mouse-exposed group were significantly more inhibitory than sera from the nonexposed control group (P less than 0.005). The effect was observed in the ammonium sulfate-precipitated immunoglobulin fraction of the mouse-exposed group's sera, and high titers of antibodies reactive with mouse spleen cells were detected in sera and immunoglobulin fractions from this group by enzyme-linked immunosorbent assay (ELISA). Embryotoxic activity was neutralized by absorption with mouse lymphocytes, but not with rabbit or human lymphocytes, suggesting that a heterophilic antimouse antibody is the factor responsible for this effect. These data emphasize the importance of including extensive controls in experiments addressing toxic effects of human sera on mouse embryos.

Mouse embryo quality control for toxicity determination in the Norfolk in vitro fertilization program

Ongoing quality control is necessary as part of the maintenance and improvement of a successful human in vitro fertilization (IVF) program. Using a mouse quality-control culture system, several instrument preparation protocols were reevaluated to determine their efficiency in the control or elimination of potential toxicity. Dilute concentrations of urine and endometrial fluid were also tested. Medium rinsed through laparoscope and aspiration needles failed to support embryo development. This effect was reversed in needles that were pretreated with rinses of Dulbecco's phosphate-buffered saline. Endometrial fluid demonstrated no obvious toxic effect, but urine-exposed embryos arrested in the two-cell state. The importance of periodic evaluation of materials and their pretreatment before use in in vitro fertilization of human oocytes is essential to ensure control of potentially toxic substances.

Mouse embryo culture as quality control for human in vitro fertilization: the one-cell versus the two-cell model

Female mice were superovulated with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) and mated with male mice. One-cell (n = 429) and 2-cell (n = 450) embryos were collected 20 and 42 hours after hCG and cultured in Ham's F-10 medium (Gibco, Grand Island, NY) (282 mOsm/l, pH 7.4) and in media of altered osmolality (260, 300, 316 mOsm/l), altered pH (7.0, 7.8, 8.0) or various dilutions of Cidex (Surgikos, Arlington, TX) (1:1000, 1:10,000, 1:100,000). Stages of development were observed for 4 days. The development of embryos in the 1-cell system was significantly impaired under all studied conditions by the 4-cell stage of development. The 2-cell system failed to detect trace amounts of Cidex in the culture media and an increase in osmolality to 300 mOsm/l. Other changes in osmolality (260 mOsm/l) and pH (7.8) were detected by the 2-cell system only at the blastocyst stage. The authors conclude that the 1-cell system is more sensitive than the 2-cell system to mild changes in in vitro fertilization culture media.

Improved pronuclear mouse embryo development over an extended pH range in Ham's F-10 medium without protein

Pronuclear mouse embryos were cultured at four different pHs (7.17, 7.27, 7.37, and 7.50) in Ham's F-10 medium (Gibco, Grand Island, NY) alone and in Ham's F-10 medium supplemented with 10% human cord serum (v/v) to assess the effects of pH and serum on preimplantation embryo development. Media used in these experiments was stored both without (old protocol) or with triple gas equilibration (new protocol). Development was assessed by the percent of embryos developing to the 2-cell stage and on to the morula and blastocyst stages. Triple gas equilibration prior to media storage improved development to the morula and blastocyst stages. Development to the 2-cell and morula stages was not adversely affected by the presence of serum, but development to the blastocyst stage was significantly higher in Ham's F-10 medium without serum at all pHs tested. In conditions without serum, percent development at all stages examined was similar over the pH range of 7.17 to 7.37, with a significant decrease in development to the morula and blastocyst stage at pH 7.50. Embryos cultured in the presence of serum demonstrated a greater decrease in the percent development to blastocyst at both the low, 7.17 and 7.27, and high, 7.50, pHs, with an apparent pH optimum at 7.37. In summary, the complex media Ham's F-10 medium supports mouse embryo development without the need for serum. Serum inhibits pronuclear embryo development to the blastocyst stage. Mouse embryo culture in the absence of serum can tolerate a pH as low as 7.17 (8.4% CO2) without any detrimental effects.

Inhibition of embryo development by some maternal sera

Blood sera obtained from patients in an in vitro fertilization and embryo transfer program at the time of oocyte retrieval were tested for their capacities to support embryo development by using them as supplements for media in which mouse embryos were cultured. The sera varied greatly in their capacities to support development of mouse embryos but there was no correlation between the effectiveness of the sera in supporting mouse embryo development and the achievement of pregnancy by the donors of the sera. The capacities of the serum samples to support embryo development also failed to correlate with any of the causes of infertility examined (endometriosis, ureaplasma infection, pelvic adhesive disease, and bilateral tubal occlusion). It was concluded that failure of maternal sera to support embryo development does not necessarily reduce the likelihood that the donors of the sera can become pregnant by in vitro fertilization and embryo transfer procedures.

Results using medium supplemented with either fresh or frozen stored serum in human in vitro fertilization

This study retrospectively compared the success of in vitro fertilization (IVF) among patients whose gametes had been incubated either in medium supplemented with freshly prepared pooled serum (331 cases) or in pooled serum which had been stored at -20 degrees C prior to use (728 cases). Frozen stored serum was as effective as fresh serum with regard to the proportion of oocytes which fertilized and embryos which implanted and was not associated with any increased incidence of fetal loss during postimplantation development.

Mouse embryo growth in different culture media: selection of a medium for quality control cross-testing of human in vitro fertilization conditions

A total of 2070 two-cell mouse embryos were recovered from 89 superovulated female hybrid mice. Six different culture media were tested. The various media supported mouse embryo development as follows (percentage mean +/- SD, n = 10): Hopp and Pitts medium (H&P) 87 +/- 5 Dulbecco's modified; Eagle's medium supplemented with 10% (volume/volume, v/v) fetal bovine serum (DMEM) 80 +/- 4; Ham's F-10 +/- 15.0% (v/v) human fetal cord serum (hFCS) 79 +/- 3; Whittingham's T-6 medium (WT-6) 60 +/- 4; Ham's F-10 +/- 7.5% (v/v) hFCS 55 +/- 5; Krebs-Ringer low bicarbonate buffer (KRLBB) 42 +/- 6. In H&P, DMEM, WT-6, and Ham's F-10 medium supplemented with hFCS, the pH was maintained within a narrow range of 7.30-7.45 and adequate level of oxygenation was achieved during 72 h in culture. KRLBB had poor buffering capacity and attained ineffective levels of oxygenation during culture. Superior mouse embryo development from two-cells to morulae and hollow blastocysts occurred in H&P, Ham's F-10 + 15% hFCS, and DMEM. Ham's F-10 medium supplemented with hFCS is routinely checked for its ability to support mouse two-cell embryo development to morulae and blastocysts. This is done in conjunction with H&P medium as the control.

Factors influencing murine embryo bioassay: effects of proteins, aging of medium, and surgical glove coatings

The 2-cell murine embryo bioassay as quality control for human in vitro fertilization (IVF) was used to evaluate the effects of protein supplements, medium aging, and surgical glove coatings. Ham's F-10 medium (GIBCO, Grand Island, NY) without protein supplementation supported growth of the 2-cell embryos to blastocysts. Addition of bovine serum albumin (BSA), fetal cord serum (FCS), or maternal serum (MS) did not enhance or reduce the blastulation rates (medium alone, 89.4%; BSA, 86.4%; FCS, 90%; MS, 74.7%). Unsupplemented Ham's F-10 medium was found to contain three major peaks of approximately 50,000 daltons and several minor peaks, analyzed on high-performance liquid chromatography (HPLC) and sodium sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), suggesting the presence of protein(s) in the medium itself. The storing of medium up to 425 days at 4 degrees C affected neither the HPLC profile nor its ability to support embryo growth (blastulation rates: fresh, 84%; stored 150 to 425 days, 77.7%). The coating of surgical gloves affected embryo growth. Both talc-coated (TC) and "talc-free," starch-coated (SC) surgical gloves were found to be progressively embryotoxic when they touched the medium for increasing lengths of time, compared with uncoated latex (UL) gloves and untouched control medium. Quality control of medium preparation and handling in murine embryo bioassay is reemphasized, with requirements for protein supplementation, use of fresh medium, and possible contamination with even talc-free, SC surgical gloves reevaluated.