THE PRESENCE OF A MITOSIS INHIBITOR IN THE SERUM AND LIVER OF ADULT RATS

Abstract

The influence of serum and tissue homogenates on the mitotic rate of regenerating liver was tested. The following fractions were injected into Sprague–Dawley rats 24 hours after partial hepatectomy: (a) serum from normal 290–340 g. rats; (b) serum from rats 24 or 72 hours following partial hepatectomy; (c) liver homogenates from normal 290–340 g. rats; (d) regenerating liver homogenates (24 hours after partial hepatectomy); and, as controls, (e) brain homogenates representing non-mitotic tissues; (f) testes homogenates representing mitotically active tissues. Serum and liver from adult animals inhibit the onset of mitosis. Serum and regenerating liver from partially hepatectomized rats, as well as heterologous tissue, show no retarding effect.The results suggest the presence of an organ-specific inhibitor of mitosis in the serum and liver of adult animals.