Pericyte-like LLMC possibly interacting with lymphocytes and endothelial cells in the aging thymus.

<p><b>A:</b> Semi-thin thymic section of middle-aged mice fixed with osmium tetroxide and stained with toluidine blue shows pericyte (green arrowhead) and pericyte-like LLMC (red arrowhead) possibly interacting with endothelial cells. <b>B:</b> TEM photomicrograph shows pericyte-like LLMC (false colored yellow) surrounding an endothelial cell and possibly interacting with various lymphocytes. White asterisk indicates elongated nucleus of a migrating lymphocyte. <b>C-E:</b> Higher magnifications of regions seen in B. Black arrowheads indicate close apposition between membranes of LLMC and thymic lymphocytes. In E, LLMC and endothelial cell share basal membrane. Asterisks indicate area of extracellular matrix that forms basal membrane <b>F:</b> PV-LLMC (false colored yellow) surrounding an endothelial cell and possibly interacting with lymphocytes in an old thymus. <b>G:</b> Higher magnification of selected area in F. Black arrowhead shows possible membrane contact between LLMC and lymphocyte. BV: blood vessel; P: pericyte. Scale bars in A: 15μm; B: 5μm; C, D: 1μm; and E: 2μm; F: 2μm and G: 400nm.