Elongation of fetal chick long bone in vitro is formed by a mitogenic activity preparation from porcine bone

Elongation of fetal chick long bone rudiments is formed by a mitogenic activity from porcine bone in vitro. Fractions of mitogenic activity from a heat- and acid-treated extract and from sequential chromatography on hydroxyapatite and from gel-filtration in 4 M guanidine-HCl increase diaphyseal elongation of metatarsals. The bone elongation-forming activity is associated with the mitogenic activity estimated by the incorporation of [3H]-methyl thymidine into the DNA of cells from embryonic chick periosteum. Histological examination of the mitogen-treated embryonic chick long bone shows that the partially purified fractions with a preferential effect on osteogenic cells increase diaphyseal elongation via cartilage cell proliferation.