Precocious differentiation of chick embryo pancreas in vitro. Roles of prednisolone, insulin and L-thyroxine

Hormonal control of pancreatic growth during fetal, neonatal and adult life

This review article has for major objective to summarize the old and latest developments on the hormonal controls of pancreatic growth. The article deals with hormonal controls during the fetal, neonatal and adult periods of pancreas development, growth and regeneration. During the fetal period, comparisons were made between studies performed with pancreatic explants and those designed in vivo. After birth, the effects of glucocorticoids, thyroxine, gastrin, bombesin, secretin, cholecystokinin alone or with secretin are reported. In the adults, similar studies were reported on hormones with addition of the effects of neuropeptides, the cell types targeted by hormones and the hormonal control after pancreatectomy and pancreatitis.

Differentiation-arrested rat fetal lung in primary monolayer cell culture. IV. Paradoxical effect of a "fetal" pO2 on precursor incorporation into phospholipids and hormone responsiveness

Differentiation-arrested lung cell cultures were developed from fetal rats of various gestational ages. In contrast to previously published observations with cultures in a pO2 of approximately 142 mm Hg, cultures developed in a pO2 of approximately 30 mm Hg, close to the normal fetal arterial pO2, have improved plating efficiency and a slightly increased growth rate. They did not, however, show gestation-dependent increases of choline incorporation into phospholipids, nor did immature lung cell cultures respond to dexamethasone or triiodothyronine, singly or in combination, by increased choline incorporation into saturated lecithin. The incorporation of choline and glycerol into lipids suggested a mature rate of lipid synthesis by immature cultures at a pO2 approximately 30 mm Hg, despite preservation of an immature morphology. Electron microscope observations revealed no gross differences between immature cultures developed at either pO2. The cellular mechanisms underlying these differences are unclear but suggest that oxygen tension may significantly influence results obtained with in vitro studies of lipid synthesis by immature lung.

Induction of fructose 1,6-bisphosphatase and glucose 6-phosphatase in fetal mouse liver

Fructose 1,6-bisphosphatase and glucose 6-phosphatase were induced in organ cultures of liver tissues from 15- and 19-day-old fetal mice, using a culture method that allowed the tissues to be maintained for 7 days in the absence of serum. In cultures from 15-day-old fetal liver, both enzyme activities increased significantly per milligram of DNA after a lag period of 1 to 3 days. In cultures from 19-day-old fetal liver only glucose 6-phosphatase increased in the absence of inducer. N6,O2'-Dibutyryladenosine 3',5'-monophosphate enhanced the rate of increase in fructose 1,6-bisphosphatase and glucose 6-phosphatase activities. The minimum effective concentration of the cyclic nucleotide was approximately 10(-6) M. Dexamethazone inhibited the increase in fructose 1,6-bisphosphatase during culture for 7 days. Glucose 6-phosphatase activity was enhanced by dexamethazone in cultures from 19-day-old fetal liver, but was without effect on glucose 6-phosphatase in cultures from 15-day-old fetal liver. The minimum inhibitory concentration of dexamethazone was less than 10(-8) M. The results suggest a complicated effect of the cyclic nucleotide on the two enzymes in fetal mouse liver as well as different mechanisms of action of dexamethazone on the induction of two enzymes.