Correlation of histopathology with ex vivo fluorescence and in vivo ultrasound images in mice with orthotopic implants of fluorescently-labeled pancreatic tumor cells. A. Ultrasound image of a small orthotopic tumor implant (upper left image; tumor indicated by arrow; Sp, spleen) whose presence was confirmed by ex vivo fluorescence imaging (upper middle image). The histopathologic findings correlated well with the ultrasound and ex vivo fluorescence findings, as shown here in this low power (1× magnification) hematoxylin- and eosin-stained permanent tissue section (upper right image). A higher magnification (100×) of the area bordered by the black rectangle in the low power image is also shown (lower image). B. Ultrasound imaging (upper left image) documented the bilobate tumor shown here, Ex vivo fluorescence imaging also demonstrated the bilobate tumor (upper middle image) contained within the pancreas. Histologic examination showed close juxtapositioning of dual tumor masses surrounded by a stretched capsule of normal pancreas (upper right image). This low power (1× magnification) image also shows the adjacent spleen, which was removed with the pancreas as an organ block to aid in orientation of the fixed tissue for histologic examination. A higher magnification (100×) of the area bordered by the black rectangle in the low power image is shown enlarged below to better demonstrate the tumor mass and the normal pancreas tissue surrounding it.