Human PCs and T cells persist within tonsil grafts. Immunohistochemistry was used to assess the cellular composition of tonsil grafts recovered at 4 weeks after surgery. (A) Postmortem examination of a xenochimeric mouse at 2 weeks after surgery showing vascularization of tonsil grafts. (B) Staining of tonsil grafts for expression of mouse (m) blood vessels; lower panel shows enlarged view of upper panel; scale bar represents 200 μm. (C) Serial sections of tonsil (before surgery) and tonsil graft (4 weeks after surgery) were stained for expression of human IgD (in red) and human CD38, CD138, CD27, and CD3 (in blue). Scale bar represents 200 μm (left-hand panels) and 60 μm (central and right-hand panels). Staining is representative of 10 tonsils and tonsil grafts.