Tissue culture explant size

In several laboratories it has been shown that normal liver and liver-derived cell lines in tissue culture release somatomedin binding proteins into the surrounding medium. In the rat, primary hepatocyte cultures (S22, S28), liver explants (B25) and isolated perfused liver (S9, S21) produce a protein of molecular mass 40-50,000. A binding species of similar size is released by the BRL 3A2 cell line (M24). Whereas somatomedin peptides could also be detected in all of these studies, human hepatoma (M22) and mammary carcinoma (B20) cell lines have been described which release the 40-50,000 molecular mass binding protein without any detectable low-molecular-mass somatomedins. Human amniotic fluid also contains a binding species of similar size (C8, D20) but, contrary to an original report that there was no detectable somatomedin (C8), it appears that both IGF-I and -II are also present (M14). 

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