In the given question there is enlargement of local lymph nodes near the infected wound. Histologically:- Presence of Macrophages, Lymphocytes, Lymphatic follicles in the coical layer and large amount of Plasma cells. It is because the antigens from the wound are going to be drained to the lymph node. These antigens will cause B cell activation, once the B cell are going to be activated, they are going to get conveed into the Plasma cell and that is responsible for causing enlargement of the lymph node. Therefore, after any kind of infection or any kind of inflammation the reactive lymph node enlargement will occur and this is explained on the basis of Antigen stimulation.