THE EFFECTS OF PANCREATECTOMY ON THE SHEEP FETUS IN UTERO

¹ Physiological Laboratory, Cambridge CB2 3EG

The effects of the removal of the fetal pancreas on the fetal metabolite concentrations and body weight have been investigated in chronically catheterized sheep fetuses during the last third of gestation. Between 390 and 1175 mg of pancreatic tissue was removed under halothane anaesthesia from sixteen fetuses between 113 and 121 d of gestation (term = 147 ± 2 d). In six fet-uses from which 928 ± 58 mg of pancreas had been removed the insulin level (3·4 ± 0·3 µu./ml, n = 6) was below or equal to the limit of sensitivity of the assay. As only very small pieces of pancreas, if any, could be found in these fetuses at delivery, removal of the pancreas was regarded as complete in these animals. Pancreatectomy was incomplete in five fetuses from which 659 ± 62 mg of pancreas had been removed. Insulin was detected in the plasma of these fetuses although the mean concentration (9·1 ± 0·7 µu./ml, n = 5) was significantly less than that in sham-operated animals (P 0·01). Small fragments of pancreas (0-26 mg) containing endocrine cells were found in these fetuses at delivery. Fetuses from which less than 50% of the pancreas had been removed had plasma insulin and metabolite concentrations similar to those of the sham-operated fetuses. Significant amounts of histologically normal pancreas were found in these fetuses at delivery. The plasma concentrations of glucose, fructose and -amino nitrogen were significantly greater in the incompletely and completely pancreatectomized fetuses than in the sham-operated animals (P 0·01). In addition, the completely pancreat-ectomized animals also had higher plasma levels of lactate and free fatty acids than the sham-operated fetuses (P 0·01). There were no significant differences in the urea concentrations between sham-operated and pancreatectomized fetuses, but the fetal to maternal concentration difference in arterial plasma urea was greatest in the completely pancreatectomized fetuses (P 0·05). The hypoinsulinaemic fetuses were significantly smaller in birth weight than the sham-operated animals (P 0·02). The results show that removal of about 70% of the fetal pancreas will produce hypoinsulinaemia in the fetus and confirm that the pancreas is essential for normal growth and development in utero.

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