Distribution of iron in the gastrointestinal tract of the common vampire bat: Evidence for macrophage‐linked iron clearance

Abstract

Iron in the tissues of the digestive tract of the common vampire bat (Desmodus rotundus) has been studied using histochemical, electron microscopic, and autoradiographic methods. This animal is an obligate sanguivore and has a daily intake of dietary iron 800 times that of man. The amount and distribution of tissue iron is not affected by either a single blood meal or starvation but does reflect the degree of siderosis of each animal's liver and spleen. By 7 days after the injection of a trace amount of 55Fe into the peritoneal cavity, labelled siderotic macrophages are present both on the serosa and within the walls of the stomach and intestine. In the lower intestine, such cells can be derived from the germinal centers of Peyer's patches. Siderotic macrophages are often situated in the lamina propria under areas of siderotic epithelium. Label is also present in the apical cytoplasm of mucosal epithelial cells, a region of abundant siderosomes. The ultrastructure of these organelles is extremely variable. Accumulations of membranous whorls and stacks, "stippled bodies," ferritin molecules, and larger "ferruginous" complexes are bounded by one or a number of membranes. Iron is excreted when these epithelial cells are desquamated into the gut lumen. Similar Prussian blue-positive granules are present in the feces. Unlike other glandular cells, the parietal cells of the fundic caecum are siderotic. Their cytoplasm contains abundant siderosomes and ferritin with accumulations of amembranous ferritin bodies in the intracellular canalicular spaces. Prussian blue-positive granules are present in the lumens of fundic glands.

Ultrastructure of the pineal body of the common vampire bat, Desmodus rotundus

“…It is less of a surprise, therefore, that siderotic macrophages should also be observed in the vampire pineal body. The ultrastructural description of siderotic macrophages observed in the vampire pineal so closely matched the one provided by Morton and Wimsatt (1980) for gastrointestinal-tract macrophages of the vampire bat that in the present investigation testing for the presence of iron within the granules was not considered. However, further histochemical tests for iron will be needed before siderotic activity can be established for the vampire pineal.…”

“…The other type of phagocytic cell (Figs. 2, 15-16), the siderotic macrophage, so identified because of its evident ultrastructural similarities with the macrophage reported in the gastrointestinal tract of Desmodus (Morton and Wimsatt, 1980), was highly irregular in shape. It had several long and slender processes which contacted other pinealocytes, coursed through the intercellular spaces, and often enclosed parts of other cells, especially pinealocyte processes (Fig.…”

“…The lipofuscin-containing cell has ultrastructural characteristics of a macrophage; and it invariably appears different from the other type of phagocytic cell which contains round to oval to irregularly shaped, membrane-bound bodies. This animal is an obligate sanguivore and has a dietary iron requirement 800 times that of man (Morton and Wimsatt, 1980). Siderotic macrophages have been described in the vampire in other locations, such as the gastrointestinal tract and the connective tissue around blood vessels (Morton and Wimsatt, 1980).…”

“…This animal is an obligate sanguivore and has a dietary iron requirement 800 times that of man (Morton and Wimsatt, 1980). Siderotic macrophages have been described in the vampire in other locations, such as the gastrointestinal tract and the connective tissue around blood vessels (Morton and Wimsatt, 1980). It is less of a surprise, therefore, that siderotic macrophages should also be observed in the vampire pineal body.…”

Distribution of Iron-Containing Granules in Lampreys, with Particular Reference to the Southern Hemisphere SpeciesGeotria australisGray

“…The accumulation of iron in the form of granules within the vacuoles of intestinal epithelial cells, which subsequently become extruded into the faeces, provides a similar means of removing iron from the body to that described by Morton and Wimsatt (1980) for the vampire bat, Desmodus rotundus. This species, which is an obligate sanguiniphore, has the problem of eliminating iron from a diet in which the intake of this metal has been estimated as 800 times that of man.…”