INVESTIGATION OF MORPHOLOGICAL-CHANGES IN ABSORPTIVE CELLS IN YOUNG-ADULT AND INFANT MICE FED DIFFERENT AMOUNTS OF IRON FOR A LONG-TERM

The changes in fine structure of the intestinal tract in young adult ( 4 week-old) and infant (2 week-old) mice fed a diet containing differe nt amounts of iron salt (Fe-0, Fe-2.5, Fe-25 : 0, 2.5 and 25 mg Fe/100 g diet. respectively) for a long term (1 or 2 weeks) were investigate d. The hepatic iron levels in infant mice fed Fe-25 for 2 weeks were s ignificantly higher than those observed after 1 week of feeding, but t here was no such increase in young adult mice during the feeding perio d. Observations of fine structure indicated typical signs of impairmen t of enterocytes due to excess iron such as the opening of intercellul ar junctions between adjacent epithelial cells and the marked appearan ce of eosinophilic leukocytes outside the basement membrane in young a dult and infant mice fed Fe-25. The frequency of the opening in interc ellular junctions increased in young adult mice fed Fe-25 for 2 weeks, but decreased in infant mice. On the contrary, under iron-deficient c onditions, the frequency in infant mice was higher than that in young adult mice. The appearance of eosinophilic leukocytes indicated that s ome immunological reaction was elicited in both groups of mice fed Fe- 25 for 2 weeks.