Tissue Culture Growth Stimulants from Ground Frozen-Dried Chick Embryos

Abstract

It has been demonstrated 1 that frozen-dried plasma and similarly treated embryo juice used in combination, after solution in distilled water, form an adequate and satisfactory medium for the growth of tissue cultures. Further experimentation with such preparations has brought forth evidence that a much more potent embryo juice could be secured if the embryos themselves were ground and frozen-dried before extraction.

Eleven-day chick embryos were removed from their shells and membranes and reduced to a gray, grumous mass with sea sand in a Ten Broeck grinder. The material was pipetted off and allowed to stand in a container for a short while to permit the larger particles of grit to settle. Later the ground substance was introduced into pyrex ampoules, frozen-dried and sealed in vacno by means of a Lyophile 2 apparatus. All manipulations were carried out aseptically.

The dried matter at first was crusty but could be reduced to a powder by forcibly shaking or by tapping the containers. The ampoules were stored at room temperature for 14 months before any tests were instituted. A preliminary series of cultures was made with embryo juice prepared by steeping a portion of the dried powder in Ringer-Tyrode's solution in an ice box prior to centrifuging. The cultures grew so exuberantly that it was decided to test statistically the growth-promoting effect of this extract on cultures of embryo chick heart.

By calculation from fresh embryos dried to constant weight in an oven; 70 mg of dry powder were equivalent to one gram of fresh embryo. This figure was only approximately accurate since there was no simple way of determining how much sand and glass dust might have been retained in the powder.