Intrathymic LLMC possibly interact with lymphocytes, epithelial and endothelial cells.

<p><b>A:</b> Representative photomicrograph of fusiform SC-LLMC (black arrowhead); and globular (yellow arrowhead) or stellate (white arrowhead) P-LLMC in middle-aged mouse thymus section. Tissue fixation with osmium tetroxide reveals lipid-droplets in brownish yellow color. <b>B:</b> TEM photomicrographs show P-LLMC (false colored yellow), adjacent to subcapsular epithelial cells (SCE) (false colored blue), possibly interacting with lymphocytes in the thymic parenchyma. Selected traced area show SCE and LLMC in the limitation between parenchyma and capsule region (Ca); <b>C:</b> Higher magnification of the selected area in panel B shows a LLMC prolongation (false colored yellow) in the basal membrane between the two layers of SCE (false colored blue), in the limit of the thymic parenchyma. <b>D</b>: Semi-thin thymus tissue sections fixed with osmium tetroxide and counterstained with toluidine blue reveal globular P-LLMC (black asterisk) surrounding four lymphocytes. <b>E:</b> TEM photomicrograph showing a lymphocyte surrounded by the P-LLMC in Panel D. Selected traced area shows limiting areas between lymphocytes and LLMC (black asterisk in the nucleus); <b>F</b>: Higher magnification of the selected area in panel E shows the nucleus (white asterisk) and plasma membrane of a lymphocyte (black arrowheads) surrounded by the LLMC with a more electron-lucent cytoplasm. <b>G:</b> A LLMC (false colored yellow) embraces a lymphocyte with a telopode-like prolongation and possibly establishes membrane contact with another lymphocyte in the old thymus. A plasma cell (PL) is located adjacent to an intrathymic LLMC. <b>H:</b> Higher magnification of selected area in G shows possible membrane contact between LLMC and lymphocyte. Black arrowhead indicates close apposition between cell membranes; <b>I:</b> A P-LLMC (false colored yellow) possibly establishing contact with a lymphocyte. Inset on the bottom left corner demonstrates higher magnification of selected area showing close apposition between the cell membranes of LLMC and lymphocyte; <b>J:</b> P-LLMC (false colored yellow) showing a telopode-like prolongation embracing thymic lymphocytes. Telocyte podom-like structure is indicated (black arrowhead). <b>K:</b> TEM photomicrograph showing P-LLMC (false colored yellow) surrounding lymphocytes close to thymic epithelial cell (false colored blue) around the perivascular space (PVS); <b>L:</b> TEM photomicrograph showing LLMC (false colored yellow) in the PVS surrounded by epithelial cells (false colored blue). BV, blood vessel. Ca: capsule; PL: plasma cell; PVS: Perivascular space. Scale bars in A: 20 μm; B, G, J, L: 5 μm; C, E, K: 2 μm; D: 15 μm; F,H: 0.5 μm; I: 1μm and inset in I: 0.2 μm.