CORRELATION BETWEEN TISSULAR AND DIVISION FUNCTIONS IN THE LIVER OF YOUNG RATS

Abstract

ABSTRACT The division and tissue specific functions are studied in the liver of young rats during the first post‐natal weeks. The division function is tested by the mitotic and the 3 H‐thymidine labelling index, the specific tissular function by the cholesterol‐7 alpha‐hydroxylase activity. The nycthemeral rhythm is triggered simultaneously for the two functions at the 20th day of life. From this time, spontaneous or induced mitoses occur during the day (rest period) and the cholesterol‐7‐alpha‐hydroxylase during the evening (period of activity). The results are explained by the influence of the hypothalamoadrenal axis, which presents a circadian activity with a maximum in the evening.