STUDIES ON THE MATURATION OF THE SMALL INTESTINE OF THE FETAL SHEEP. I. THE EFFECTS OF BILATERAL ADRENALECTOMY

The effect of bilateral adrenalectomy at 120 d gestation on subsequent maturation of proximal and distal small intestine was investigated in chronically catheterized fetal sheep. Ten adrenalectomized and fourteen controls were examined at 136 d; some following infusion of [ 3 H]thymidine at 3-6 d or 4 h before termination of pregnancy. Mean plasma cortisol levels were 5·3 ± 0·7 ng/ml in the adrenalectomized group; control values ranged from 14 to 39 ng/ml level during the 2-week experimental period. Fetal body growth was significantly increased following adrenalectomy. In the small intestine, growth of mucosal structures was reduced, especially in distal regions. Villus height was significantly reduced in both regions. External muscle thickness was significantly increased in both regions. Despite these changes there was no alteration in villus enterocyte morphology, nor were there any significant changes in villus or crypt densities. The proportion of crypt cells labelled with [ 3 H]thymidine was unaffected by adrenalectomy. In proximal regions, migration rate of labelled enterocytes declined from 12·0 to 5·83% villus height/d ( P 〈 0·025) after adrenalectomy; there was no change in migration rate in distal regions. The estimated renewal time was greater in both proximal and distal regions in adrenalectomized compared with control fetuses.