TLR3 immunostaining in human neuroblastic tumors. (A) TLR3 expression in ganglioneuroma (GN) and (B) in ganglioneuroblastoma (GNB). More than 50% of the ganglion cells (asterisk) and some neuroblastic cells (arrow) in GNB tissues exhibited prominent TLR3 staining. (C) TLR3 expression in differentiated NB tissues. Some neuroblastic (arrow) cells and sporadic ganglion cells (asterisk) exhibited TLR3 staining. (D) TLR3 expression in the undifferentiated NB tissues. Very few neuroblastic cells were positive for TLR3 expression. Original magnification, 200×.