An electron micrograph (EM) showing an antigen transport cell (ATC) in the subcapsular sinus (SS) of a popliteal lymph node (LN) 1 minute after subcutaneous introduction of the antigen into the foot of an immune animal. The popliteal LN drains the tissue fluid (lymph) from the foot region of the body. In this experiment the question of the transport of antigens [such as horseradish peroxidase (HRP)] to lymphoid nodules (follicles) in the lymph node cortex was studied. The antigen, HRP was identified in electron micrographs as a black precipitate detectable with a reaction for peroxidase. In this EM a relatively large cell is seen in the subcapsular sinus with the black antigenic material associated with its surface. The surface of this cell has "flap-like" veils. It is these veils that are coated with the antigen (black material). On the left side of the cell, these veils are freely visible and are coated with a granular black precipitate. On the rest of the surface of the cell because it is squeezed tightly into the SS, these veils are flattened against the cell body. These veils are also coated with the antigen. Thus, it may be said that this cell arrived to the lymph node SS in the lymph while transporting the antigen on its surface. This ATC was otherwise identified as a veiled-like cell. For more details on this study click on the REF button.