Figure 2. Histopathological features of primary and metastatic NOS.

(A) Histology of representative NOS tumors stained with hematoxylin and eosin (H&E) showing poorly differentiated OS with high cellularity and scattered mitoses (white arrow, top left), and invasive infiltration of tumor cells into surrounding muscle tissue (blue arrow, top right) and fat (blue arrow, bottom left), but not nerves (bottom right). Scale bars, 50 μm.

(B) H&E-stained sections of representative lung metastatic OS mass (blue arrow) showing high cellularity at high magnification (right). Scale bars, 500 μm (left) and 50 μm (right).

(C) Photo of a mouse lung lobe (left), which was harvested from a tri-transgenic mouse (Rosa26^NICD; Col1a1 2.3kb-Cre; Rosa26^LacZ) with whole mount X-gal staining shows a metastatic lesion (blue) that could not be detected macroscopically. Lung section counter-stained with eosin (right) showed that LacZ was only expressed in tumor cells (blue) but not in lung cells. Scale bars, 50 μm.

(D) Immunofluorescent images stained with GFP (green) and DAPI (Blue) in lung metastatic tumor at low (top panels, scale bars, 200 μm) and high (bottom panels, 20 μm) magnification.

See also Figure S2