There are many publications on pH that make the in vitro embryo culture system what it is today.  This month, we have collected examples of articles on pH and embryo culture that every embryologist interested in understanding their culture environment should read.

BCSI prides itself on informing our customers with useful information to best optimize embryo culture and give their patients the best chance of success. To support this goal, we have selected an essential pH/embryo culture article for four different categories to give you a quick and thorough brush-up on pH and culture media.

The Fundamental pH Article:
Title: Optimizing pH in Clinical Embryology 

The pH in Embryo Culture Review:
Title: Optimizing the culture environment in the IVF laboratory: impact of pH and buffer capacity on gamete and embryo quality

The Embryo Culture System Review:
Title: Optimizing the culture environment and embryo manipulation to help maintain embryo developmental potential

The Hot Off The Presses pH Article:
Title: pH: the silent variable significantly impacting meiotic spindle assembly in mouse oocytes 

Summary:

If I had to choose one paper for junior embryologists to read when they are hired, this publication would be it. Dr. Pool outlines the required chemistry knowledge to understand pH in a bicarbonate-buffered system. The detailed chemistry lesson includes an easy to follow derivation of the Henderson-Hasselbach equation while referencing the historical context behind the chemistry of equilibration.

Dr. Pool then continues by applying the basics of pH to the effects pH has on human embryo development.  Dr. Pool references the excellent work by Dale et al. (1998) to establish the historical “gold standard” media pH of 7.4, as well as the work of Karen Phillips under Dr. Baltz to determine the internal pH of cleavage stage embryos and refine the acceptable media pH range.

He finally concludes with a robust warning to remember that the pH values are dynamic rather than static and that % CO2  values are not sufficient to understand the effects of culture environment on your embryo development.

Dr. Pool has graciously allowed BCSI to provide this critical article to our customers. A PDF download of the article is available on our website. 

Summary:

This pH review article is a fantastic document to save as a general reference.  Differences between external pH (pHe) and internal pH (pHi) are compared and contrasted throughout the paper, giving the reader a full scope of knowledge on how pH effects embryo development. The article also covers in detail common buffer systems used in cell culture and the buffering capacity of various Good’s buffers such as HEPES, DIPSO, and MOPS in differing concentrations and combinations.

The review gives a nod to Dr. Pool’s article by referencing a graphical demonstration of pH fluctuations during use of fyrite and digital CO2 detection equipment. Recommendations on best practices using a pH meter and how best to calibrate and collect values are also included. If you want a quick understanding of pH in the IVF culture system, this is your best bet.

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Summary:

This paper is a robust analysis of the current embryo culture system. Media composition is covered in refreshing detail, including information on the concentration of critical media components found in commercial embryo culture media. This article also gives some foresight into the future of culture media composition, including the use of dipeptide amino acids and macromolecule supplementation.

Common variables controlled through the incubator are also covered, including varied oxygen concentrations, temperature, and media pH. There is a thorough discussion of the history, potential benefits, and continued study attempts into coculture systems. The section on biomimetics (or, mimicking nature to solve complex problems) is fascinating and covers some of the less well-known or used dynamic embryo culture techniques such as tilting, vibrations, and pulsatile flow.

Finally, ART technologies such as embryo biopsy and cryopreservation are also covered in relation to culture conditions. Biopsy technique in relation to embryo stage is covered, as is vitrification in embryos and the effects of vitrification on the oocyte. Overall, an incredibly well-balanced read that will get you up to speed in a relatively short time.

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Summary:

This is a brand-new study looking into the effect of media pH on meiotic spindle integrity and assembly. While animal model comparisons have their limitations, this recent data on the effects of media pH may still have great significance in the ART world.

The article discusses the natural functionality of the spindle in chromosome segregations, as well as techniques to visualize the spindle fibers and a discussion of the use of the retardance value, a proportional comparison of the number of microtubules in the spindle.

The results collected are of significant substance, including images of the MII oocytes with a clear polar body and spindle positioning, values for mean spindle retardance when cultured in pH-specific formulated embryo culture media, and data on heated scope temperature fluctuations inside of culture media drops. The author also analyzes the previous literature on relating spindle analysis and ART outcomes. The findings of this study reinforce that IVF laboratory conditions and variables should be controlled as well as is functionally possible in the embryo culture system.

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Have embryology or culture media questions or topics you would like to discuss? Feel free to contact me with your suggestions, and they could be addressed in our upcoming web email series.

Embryology Product Specialist
Blood Cell Storage, Inc.
Tel: +1.425.654.8462 (D)
Email: susan.olds@safesens.com