Ultrastructure of Macrophages and Karyolytic Bodies in Small Intestinal Villi of Macaque Monkeys and Baboons

Abstract

Abstract. Macrophages in the lamina propria at the tips of small intestinal villi in 41 of 5 1 macaque monkeys were filled with eosinophilic, autofluorescent, periodic acid-Schiff-positive globules, hematoxyphilic and Feulgen-positive granules, vacuoles, and iron and lipochrome pigments. The Feulgen-positive granules were seen ultrastructurally in macrophages of nine of 15 clinically normal macaques and baboons. Four of the 15 had similar granules in the intercellular spaces of the epithelium. Ultrastructurally, the eosinophilic globules were electrondense phagolysosomes; the Feulgen-positive granules resembled nuclei of lymphocytes in various stages of pyknosis. Cytoplasmic organelles enclosed in rnembrane-bound vacuoles were present in the intercellular spaces of the epithelium of one monkey. Similar organelles were phagocytized by macrophages in another monkey. Feulgen-positive granules have been reported in villi of normal rodents. In all other species, including man, degenerating nuclei called "karyolytic bodies" and other evidence of enterocyte or lymphocyte degeneration have been considered abnormal concomitants of irradiation and antimitotic therapy. The significance of the findings in monkeys is not known, but they may represent a subclinical disease process.A characteristic histologic finding in necropsied macaque monkeys (Macaca) and baboons (Pupio) is many macrophages in the tips of small-intestinal villi. These cells contain cytoplasmic inclusions, such as pigments, eosinophilic globules, vacuoles, and basophilic granules. Such cells have not been reported in man [6,8, 291, and in the author's experience are not common in the villi of New World monkeys and domestic animals. Macrophages containing phagocytized nuclear debris have been described in the tips of villi of normal laboratory rodents [l, 5 , 211. The significance and morphogenesis of these "karyolytic bodies" in these species have not been established. T h e karyolytic bodies in small and large bowel, however, have been considered a significant lesion in several species with various diseases [7, 10,14,15,19, 261. They were considered significant effects of proton irradiation in Macaca mulatta [lo]; the authors seemed unaware, however, that such bodies also occur in macaques that die of many different diseases, and in clinically normal macaques. Macrophages with nuclear debris probably have been seen often in intestinal villi of 121

Characterizing the Natural History of Acute Radiation Syndrome of the Gastrointestinal Tract: Combining High Mass and Spatial Resolution Using MALDI-FTICR-MSI

“…The intestinal mucosa has the largest reservoir of macrophages and the villi tip of the rhesus macaque has been shown to contain a high number of macrophages. The images of PG(18:2/18:2) and PG(18:1/18:2) presented here correlate with the images of macrophages in the villi tips as reported by Bronson et al (Bronson 1981). PG(16:0/18:1) distributed in the lamina propria around the crypts and PG(18:2/18:2) and PG(18:1/18:2), distributed in the lamina propria at the villi tips, demonstrated some recovery in several animals at days 15 and 21.…”

“…PG(18:2/18:2) and PG(18:1/18:2), both containing di-unsaturated FAs displayed a highly localized distribution in the lamina propria at the villus tip, with much lower signal intensity in the rest of the lamina propria and little to no signal in the muscularis externa. These specific distributions within the lamina propria are believed to be associated with distinct populations of immune cells as the villi tip in NHP were shown to contain predominantly macrophages, a phenomenon only observed in macaques (Bronson 1981). Whereas the lamina propria surrounding the crypt regions were populated with lymphocytes and a few neutrophils and monocytes, and the increased detection of PG(16:0/18:1) here was believed to be associated with these cells.…”

In vivo spectral imaging of different cell types in the small intestine by two-photon excited autofluorescence

“…The lipopigment lipofuscin is found in granules of 1-5 μm size within the cytoplasm of metabolically active cells, such as the retinal pigment epithelium 38 and has been described also in enterocytes. 39 Lipofuscin has a high two-photon action cross section, 15 and its excitation maximum covers the broad range from 700 to 850 nm, which corresponds well to the excitation spectra of lysosomes measured in the present study ( Figs. 9 and 10).…”