Cultivation of post-implantation mouse and rat embryos on plasma clots

Mouse and rat embryos of primitive streak to early somite stages have been grown on clots of plasma and embryo extract.

Of nineteen mouse embryos explanted at 8–12 somites, seventeen acquired a blood circulation and thirteen developed to limb bud stages with 24–32 somites.

Of the mouse embryos explanted at 1–7 somites, 72 per cent, developed a blood circulation and 33 per cent, went on to limb bud stages.

Of the mouse embryos explanted at head fold and head process stages, 60 per cent, developed over 8 somites and 26 per cent, a blood circulation.

Mouse embryos explanted at primitive streak stages developed neural folds and a few somites, but not a blood circulation.

Twenty-two rat embryos explanted at 6–12 somites acquired anterior limb buds and 25–30 somites.

Eighty-five rat embryos explanted at head process or head fold stages mostly became 6–12 somite embryos with beating hearts. Only four formed a blood circulation.

The rate of development in vitro, at least for the first 24 hr., was about the same as in vivo. The maximum amount of development obtained in vitro was equivalent to about 40 hr. in vivo. Often the blood continued to circulate for over 48 hr., and the heart to heat for over 72 hr.

Addition of 4-5 per cent. CO₂ to the air in the culture vessels was found to be beneficial. Increasing the O₂ to 60 per cent, improved the development of the older, but not of the younger embryos.

It appeared immaterial whether the embryo extract used in the culture media was obtained from chick or mouse.