Letter | Published:

Localization of Inhibitors of Neural Differentiation in Chick Embryos

Nature volume 192, pages 997998 (09 December 1961) | Download Citation



IN testing the hypothesis of specific inhibition in cellular differentiation, I have shown1 that early chick embryos, when cultured on a nutrient medium which has incorporated in it supernatants of adult and embryonic brain extracts, displayed homologous brain defects in a significant number of cases. Since the preparation of subcellular components has become a standard technique for problems of cellular chemistry (see review by Allfrey2), this investigation was prompted with the hope of localizing the inhibitory material in the crude brain extracts to a particular cell fraction. Accordingly, chick brains were homogenized and subjected to differential centrifugation in order to obtain mitochondrial, microsomal, and soluble protein fractions. Earlier investigations of Braverman3 and Lenicque4 showed that the nuclear fraction is not involved. The procedure used for culturing chick embryos was that of Spratt5. Since I have found1 that stages 4 and 5 (ref. 6) are the crucial stages for treatment with brain extracts, the assay for inhibitory activity was restricted to the use of these stages.

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    • A. K. KATOH

    Postdoctoral Fellow of the U.S. National Science Foundation.


  1. Biological Institute, Nagoya University, Chikusa-ku, Nagoya.

    • A. K. KATOH


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