Liver regeneration on chicken chorioallantoic membrane

To explore how the liver regenerates, liver pieces from 15-day-old chicken embryos were grafted onto the chorioallantoic membrane (CAM) of 9-day-old chicken embryos and cultured for 11 days at the longest. The cultured liver pieces were examined histologically. The liver implants were gradually engulfed into the CAM and underwent necrosis of hepatocytes, except in their peripheral areas, during the first 1-4 days after grafting. Surviving cells in the peripheral areas began to proliferate 4 days after grafting. Thereafter, the cells were assembled into normal liver tissues and represented almost all the areas of the implants 9 days after grafting. Only after penetration of blood vessels from CAM did the liver implants enter a phase of rapid regeneration to form well-organized liver tissues. At the early stage of regeneration, the cells at the peripheral areas did not produce albumin, but reproduced it in the regenerated liver tissues, implying that hepatocytes restored their functions that were temporarily lost in the process of regeneration. Thus, we concluded that the liver pieces from 15-day-old chicken embryos had the ability to form normal liver tissues on CAM and that the blood supply played an important role in liver regeneration.