Uptake and intracytoplasmic storage of pigmented particles by human CD34+ stromal cells/telocytes: endocytic property of telocytes.
Bottom Line: Our results demonstrate that CD34+ TCs have endocytic properties (phagocytic-like TCs: phTCs), with the capacity to uptake and store India ink particles. phTCs conserve the characteristics of TCs (long, thin, bipolar or multipolar, moniliform cytoplasmic processes/telopodes, with linear distribution of the pigment) and maintain their typical distribution.Our ultrastructural observation of melanin-storing stromal cells with characteristics of TCs (telopodes with dichotomous branching pattern) favours this possibility.In conclusion, intestinal TCs have a phagocytic-like property, a function that may be generalized to TCs in other locations.
Affiliation: Department of Anatomy, Pathology, Histology and Radiology, Faculty of Medicine, University of La Laguna, Tenerife, Spain.Show MeSH
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Mentions: Pigment was evident in macrophages, which were wandering in the stroma or accumulated near to vessels in the enteric wall and extraintestinal adipose tissue (Figs 1A and B, 2E, 6B and 7). In the lymph nodes, macrophages were observed in the intranodal sinuses. Macrophages displayed a rounded, oval or irregular morphology and abundant intracytoplasmic pigment. Furthermore, the pigment in macrophages appeared in thick granules or aggregates of granules, which occupied most of the cytoplasm. These cells expressed CD68 (Fig. 7A and B) and CD45 (which were only detected in the scarce cytoplasm unoccupied by the pigment), but were not stained by anti-CD31, anti-CD34, anti-αSMA or anti-h-caldesmon. In the enteric wall, macrophages were scarce in the muscular propria and plexuses, and more abundant in submucosa and serosa. Ultrastructurally (in pigmented melanocytic nevi), the cytoplasm of macrophages was packed with accumulated pigment particles (Fig. 7C). The particles appeared within membrane-limited lysosomes, whose shape, size and internal structure varied considerably. No transitional forms between phTCs and macrophages were observed.
Affiliation: Department of Anatomy, Pathology, Histology and Radiology, Faculty of Medicine, University of La Laguna, Tenerife, Spain.