Baltz J M, Biggers J D
Laboratory of Human Reproduction and Reproductive Biology, Harvard Medical School, Boston, Massachusetts 02115.
Mol Reprod Dev. 1991 Apr;28(4):351-5. doi: 10.1002/mrd.1080280407.
The standard method for culturing small preimplantation mammalian embryos is a system in which they are placed into microdrops of culture medium under oil. Thus the source of oxygen for the embryos lies beyond two liquid phases--medium and oil. If transport of oxygen is not sufficiently rapid to replace that consumed by the embryos, the medium could become depleted of oxygen. Over small distances, the dominant means by which oxygen is transported through liquid is by diffusion. Our calculations show that diffusion alone is sufficient to supply oxygen to mouse embryos; there is virtually no perturbation of the oxygen concentration when there are up to 10 embryos in the drop, and 50 embryos produce a drop in oxygen tension that is not large enough to have a deleterious effect. Furthermore, diffusion is probably not the dominant mechanism by which oxygen is transported to the embryos; on the scale of these microdrops, convection is faster and would serve to mix the drop so that anoxic regions cannot develop. Therefore, we conclude that even a relatively large number of embryos in a culture drop do not significantly deplete oxygen.
培养小型植入前哺乳动物胚胎的标准方法是将它们置于油下的培养基微滴中。因此，胚胎的氧气来源位于两个液相——培养基和油之外。如果氧气的运输速度不够快，无法补充胚胎消耗的氧气，培养基中的氧气可能会耗尽。在短距离内，氧气在液体中运输的主要方式是扩散。我们的计算表明，仅靠扩散就足以向小鼠胚胎供应氧气；当微滴中有多达10个胚胎时，氧气浓度几乎没有扰动，而50个胚胎会使氧气张力下降，但下降幅度不足以产生有害影响。此外，扩散可能不是氧气运输到胚胎的主要机制；在这些微滴的尺度上，对流速度更快，会使微滴混合，从而不会形成缺氧区域。因此，我们得出结论，即使培养微滴中有相对大量的胚胎，也不会显著耗尽氧气。
