The effect of hydrocortisone on the accumulation of amylase in embryonic chick pancreas

During the late stages of development of the chick embryo amylase and other exportable enzymes accumulate rapidly in the pancreas from about 17 days of development until 2 days after hatching (develop mental age 22 days) [l-3] . Although this phase of rapid accumulation of digestive enzymes is dramatic and apparently plays a vital role in pancreatic development, it is clearly the consequence of the maturation of an already highly differentiated organ [4]. immediately prior to the maturation phase (from 12 to 16 days of development) amylase specific activity remains constant. These observations implied that there must be an early phase of differentiation before 12 days of development, which should be characterized by the rapid accumulation of amylase. The present study shows that there is indeed an early phase of differentiation which starts before 6 days of develop ment and that during this phase, which ends at 12 days of development, the specific activity of amylase increases by more than 2 orders of magnitude. Pancreases from 7-day embryos cultured in vitro underwent a limited degree of differentiation as indicated by the accumulation of amylase. The rate of accumulation of amylase in pancreas cultured in vitro could be greatly increased by adding hydrocortisone to the medium even after accumulation in the absence of the hormone had stopped.