Figure 2. Morphological features in thyroid glands and metastasis of TRβPV/PV mice. Histological sections from tissues of TRβPV/PV mice stained with hematoxylin (blue) and eosin (pink) show evidence of capsular invasion (A) (arrows) and vascular invasion in thyroid (B) (arrow), spindle cell anaplasia within the thyroid shown at higher magnification (C) (arrow), and a cardiac metastasis (D) (arrow). Capsular and vascular invasion are the pathologic features used in the diagnosis of human neoplastic thyroid tumors. The pathologic progression of thyroid cancer in TRβPV/PV mice is similar to that in humans.