A 12-year-old boy presents with a 5-day history of sore throat. His temperature is 38.7degC (103degF). Physical examination reveals inflamed tonsils and swollen cervical lymph nodes. Trafficking and recirculation of blood-borne lymphocytes through the cervical lymph nodes in this patient occurs primarily at which of the following locations?

High endothelial venules (HEVs). B and T lymphocytes circulate via the vascular system to secondary lymphoid organs and tissues. Included among these tissues are lymph nodes, mucosa-associated lymphoid tissues, and spleen. In the case of lymph nodes, lymphocyte trafficking occurs through specialized postcapillary venules termed high endothelial venules (HEVs). HEVs express an array of specific cell adhesion molecules (e.g., CD31) that allow lymphocyte binding and diapedesis. The cuboidal shape of HEV cells reduces flow-mediated shear forces and specialized intercellular connections facilitate egress of lymphocytes out of the vascular space. Afferent and efferent lymphatic channels (choices A and B) do not possess HEVs. Hassall corpuscles (choice C) are found in the medulla of the thymus. Peyer patches (choice E) are organized lymphoid tissues found in the small intestine.Diagnosis: Lymphadenopathy, streptococcal pharyngitis