MORPHOLOGICAL-CHANGES IN THE ESOPHAGUS OF NEWBORN PIGS - EFFECTS OF AGE, DIET AND ORAL INSULIN-LIKE GROWTH-FACTOR-I (IGF-I) OR IGF-II

It has been reported in the literature that the stomach and the intest ine in newborns undergo profound growth and functional maturation duri ng the immediate postnatal period and diet ingestion has a significant impact on these changes. The present paper examines oesophageal devel opment in newborn pigs during the first three postnatal days and the e ffects of diet and oral insulin-like growth factor I (IGF-I) or IGF-II on oesophageal morphology. It was observed that marked changes, inclu ding reduction in thickness of the epithelium, accelerated proliferati on and migration of basal epithelial cells and increased accumulation of mucus in the glandular cells, occurred during the first postnatal d ay following onset of natural suckling. Bottle-feeding with various li quid diets (i.e. porcine colostrum, bovine colostrum, bovine milk, and infant milk formula), induced marked morphological changes which were similar to those induced by natural suckling. However, bottle-feeding with water did not result in marked reduction in the thickness of the epithelium nor did it accelerate basal epithelial cell proliferation and migration. Oral IGF-I, but not IGF-II, increased basal epithelial cell proliferation up to 81%. Owing to a large inter-animal variation, the increment did not reach a significant level (P = 0.071). The resu lts suggest that chemical constituents in the diet and physical stimul ation of food ingestion, which cause sloughing off of luminal surface tissue, are two major stimuli of epithelial cell proliferation in the newborn oesophagus.