Mouse Embryo Assay, MEA test is the legal requirement for release of new media batches, however, The Bovine Embryo Assay (BEA) test is an extremely important addition!
ARTSMedia Denmark’s media batches are regularly monitored through BEA tests which are also an important part of our Research and Development.
There are huge differences in reproductive physiology between the mouse and a woman, obviously also between a cow and a woman. The most obvious similarity in cow and woman is gestation time and that they don’t give birth to litters like mice.
However, the MEA test is considered sufficient for quality control release of ART media. When media are tested in the BEA, that all have passed MEA, they often give significantly different blastocyst rates as well as considerable morphologic and kinetic differences in the BEA test.
In vitro oocyte maturation (IVM), is at the moment not a standard procedure in human ART as it is and has been for decades in bovine ART. Therefore the BEA test includes quality control of all steps of the procedure, IVM, IVF and IVC.
In addition, fertilization and capacitation are species specific and a MEA test mostly assesses blastocyst development from either one-cell or two-cell stage embryos. Should a batch variation occur it will not be detected in a MEA test, where release parameter is > 80 % blastocyst rate. In the BEA test, however, a difference in medium quality can be detected even though the medium has passed the MEA test. For instance, 35 % vs 55 % blastocyst rates indicate two media are different, however both media will have passed the MEA. Hence, the MEA is a mere toxicological bio-assay, whereas the BEA also provides functional and performance data.
Therefore, we have decided that several batches will undergo the BEA test in addition to the required MEA Test.
Ovaries from slaughterhouse cows are collected, and in the laboratory the oocytes are aspirated from all follicles larger than 3 mm. Approximately 8 oocytes per ovary is on average obtained. They are subsequently matured, fertilized and cultured. The media are tested and blastocyst rates, kinetics and morphology are evaluated as well as hatching rates. The average blastocyst rates in the BEA test are between 40-50% and thus indicate performance differences, whereas 80 – 90 % blastocyst rates in the mouse embryo assay (MEA) test only indicate whether the medium is toxic or not.
Only in glass bottles can you maintain stability of the active compounds in the media for up to 18-24 months. Plastic will decrease quality of media over time and even contribute to toxicity and will always have a limited shelf-life. The entire batch must be manufactured in one day. That means that no stock solutions should be stored for a longer period of time and that the entire batch should be manufactured and bottled within the same day and not stored overnight.
Every single batch is provided with a batch certificate stating that sterility, fungal and endotoxin tests have been performed and passed quality control specifications.
For some products or batches the quality data may currently not be available on-line, to receive the certificate of analysis click here.
Virtues and limitations of the preimplantation mouse embryo as a model system
Robert A Taft Theriogenology.
Read the full article here: https://doi.org/10.1016/j.theriogenology.2007.09.032
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Oocyte diameter (μm)
Stage at zygotic genome activation
Time to reach
2-cell stage (hours)
Mouse and bovine models for human IVF, December 2002, Reproductive Biomedicine Online 4(2):170-5
Amino acid uptake and utilization also differ among species with mouse embryos not requiring amino acids to develop to the blastocyst stage, in contrast to bovine and human embryos.
Mouse embryos are less sensitive to and recover more easily from changes in pH than either human or bovine embryos.
The ability to utilize glucose varies among species. Human embryos do not utilize glucose due to limited availability of hexokinase. The situation is more complicated for the mouse, as embryos from some strains can metabolize glucose while others cannot. Cattle embryos are able to metabolize glucose, although this is affected by culture conditions .
Some of the controversy regarding the perceived value of the mouse embryo assay is likely the result of the conditions under which the assay was conducted. The strain of mouse used, stage of embryo used and the culture conditions employed may also affect the outcome. Thus, embryos from inbred strains may provide a better model, and the developmental stage of the embryo will also impact the result. For instance, one-cell embryos are more sensitive than two-cell, four-cell or eight-cell embryos.
Finally, the type of media also influences the assay. For instance the absence of protein in the media improves the sensitivity of the assay.
ISO standards are internationally agreed by experts and when a factory is certified it ensures state-of-the-art manufacturing in a controlled environment and is your assurance of quality.