Tissue culture media; the essential non-dialyzable factors in XXXX placental cord serum.

@entity1 @entity137 @entity3636 @entity7935 @entity4543 @entity35 @entity1718 @entity291
1. @entity1 placental cord serum contains a factor or factors necessary for active growth of fibroblasts in tissue culture and a factor which prevents the appearance of a characteristic @entity137 . 2. The growth-promoting factor(s) is stable to heating to 60 degrees C. for 30 minutes and is associated with the euglobulin fraction of the serum. 3. Extraction of dried cord serum with @entity7935 , @entity3636 , and @entity4543 does not cause any decrease in growth-promoting activity. 4. Sera from hypophysectomized, adrenalectomized, and thyroid-parathyroidectomized @entity35 show as much growth-promoting activity as normal @entity35 sera. 5. @entity291 gamma globulins, anterior pituitary growth hormone, and insulin do not replace the serum growth factor. 6. The @entity137 -preventing factor is serum albumin. 7. Evidence is presented that the @entity137 is due to free @entity1718 in the medium and that serum albumin acts by binding the @entity1718 .
