Cellular distribution of orally and intramuscularly administered iron dextran in newborn piglets.

Histochemical studies were performed on tissues from piglets of different ages treated orally with iron dextran soon after birth. The mucosal cells in the distal region of the small intestine were heavily laden with stainable iron granules during the first three days after the iron administration. The absorptive epithelial cells are desquamated within seven to ten days after birth. Consequently, the number of iron granules gradually diminishes during the first seven days after treatment and no iron granules are demonstrated 12 days after the administration of iron. The iron dextran complex is pinocytosed in newborn piglets and then transported via the lymphatic system. Thus the sinusoidal lining cells of the body and mesenteric lymph nodes are already heavily laden with iron granules 24 hours after oral treatment. This iron store is released only slowing during the first weeks of life. Great amounts of iron granules are demonstrated in the liver and spleen macrophages during the first week after the administration of iron. Due to the rapid utilization of iron in growing piglets these iron stores diminish sharply during the weeks following birth. The distribution of stainable iron in the lymph nodes, liver and spleen seven days after intramuscular injection of iron dextran in newborn piglets was comparable to that for oral administration at that stage of the experiment.