Plate 2: Representative Micrographs of Thymus Using Immunoperoxidase Staining for CD3. (A, B) Control rat tissue showing numerous strong positive brown immuno-reactions for T-lymphocytes (arrow) mainly in cortex (C) enclosing medulla (M) with weak immunoreaction. (C, D) MSG-treated rat tissue with weak positive immunoreactions for T-lymphocytes (arrow) in cortex and moderate immunoreactions (thick arrow) is noticed in medulla. (E, F) Recovery group rat tissue showing T-lymphocytes (arrow), mainly in cortex (more so than in medulla). (Images scale bar, C,E; 100 μm & D, F; 25 μm)