Morphological and biochemical effects of glucocorticoids in chick embryo hepatocytes during development.

The administration in ovo of hydrocortisone-21-phosphate caused, in chick embryo liver, a reduction of the number of hepatocytes which can be isolated from 1 mg dry weight of liver and a marked increase of their size. Moreover, the treatment diminished the incorporation of thymidine into acid-insoluble fraction in these cells whilst it augmented the content of protein, RNA, DNA and the level of thymidine kinase/cell. These effects were highest at 8-10 days, then declined with the age, disappearing after 18th day of incubation. Similar effects were obtained by injecting other glucocorticoids or ACTH. Combined treatment with metopirone abolished the effects found with ACTH, but did not modify the action of hydrocortisone. These findings suggest that glucocorticoids interfere with the proliferative cycle of hepatocytes by inhibiting the mitotic phase and favouring the production of abnormally large cells.