HETEROGENEOUS INDUCTIONS IN THE CHICK EMBRYO

Abstract

Chick embryos at stages three and four were explanted to a saline–albumen– agar medium and incubated for a further 30 hours at 38° C. All were reasonably normal embryos and had reached stages of development comparable to in ovo standards. Chick embryos at the same stages of development and containing a small Fragment of coagulated liver, kidney, or Hensen's node or live Hensen's node in contact with the under side of the epiblast were similarly explanted and cultivated. A large number of successful inductions of secondary neural axes was obtained with liver, kidney, and Heusen's node as inductor. No inductions were obtained with killed Hensen's node as inductor.Rectangles of epiblast taken outside of the presumptive neural area of stage three–four embryos were isolated and cultured on the same medium. These showed no neural differentiation tendencies. Similar areas of epiblast, cultured with fragments of coagulated liver or kidney, developed a large number of neural inductions.