Abstract
It is frequently difficult during the winter months in certain localities to obtain the adequate and inexpensive supply of fertile eggs so Essential where constant supplies of embryo juice are required for procedures in tissue culture. Two methods were devised for utilizing chick embryos from which growth-promoting extracts might be made while a plentiful supply of embryos was available.
Embryo Broth. Five hundred grams of finely chopped embryos were steeped in one litre of Tyrode's solution for 24 hours in a refrigerator and then heated for 2 hours in an Arnold steam sterilizer. The resulting broth was strained through fine cheese cloth and as much fluid as possible forced from the cooked tissue. Ten grams of peptone and 5 gm. of sodium chloride were added, the whole filtered through paper and made up to one litre with Tyrode's solution and sterilized in an Arnold steamer for 30 minutes. This fluid was the concentrated stock solution. Portions of it were diluted with Tyrode's solution to make a 2% solution, adjusted to pH 7.6, sterilized in flasks in an Arnold steamer for 2 hours and stored at 30°F. in a refrigerator. The final fluid was used in lieu of fresh embryo juice.
Frozen Embryos. Eight-day chicks were removed aseptically from their shell and placed in sterile section dishes—2 or more to a dish. These were placed in a larger, sterile, glass-covered container and stored at 10°F. in a refrigerator. From these frozen embryos, 25% embryo juice could be made in the usual manner at any time.
The broth and frozen embryos were kept in storage, as described, for 6 months and were thereafter tested for growth-promoting substances against embryo juice made from fresh 8-day embryos.
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