Histological and immunohistochemical analysis of teratomas.

Hematoxylin/eosin staining shows teratomas derived from wild type (A) and mutant (B) ES cells that are composed of a variety of differentiated cells. (C–D) Perlecan immunofluorescent labeling in wild type (C) and mutant (D) teratomas. In wild type perlecan is expressed in the stroma (s), and in BMs surrounding vessels (arrow in C) and other structures including glands. Perlecan-null teratomas also have perlecan expression in the tumor stroma (s) and vessels. (E–F) Double fluorescent labeling with PECAM-1 in red (E) and perlecan in green (F) reveal that the vasculature of the perlecan-null tumors is composed of a mixture of perlecan-positive (host-derived) and perlecan-negative (ES cell-derived; arrowheads) endothelial cells. (G) Quantification of perlecan-positive and perlecan-negative vessels per area in wild type (n = 10) and mutant teratomas (n = 10). Bars: (A–D) 250 µm; (E–F) 125 µm.