Figure 7.

Effect of splenic movement/vagal denervation on the splenic mesothelium.

Panel a; Shown is a spleen harvested from a surgical control rat (top; laparotomy only) and rat in which the spleen was moved to midline during surgery. Surgery was performed on both rats 28 days prior to tissue harvest. Fibrosis of parts of the splenic capsule (arrow) can be observed in spleens harvested from rats in which the spleen was manipulated to midline during surgery.

Panel b; Shown is trichrome stained image of the splenic capsule (original magnification 20×) demonstrating thickening on the capsule (blue staining) and mesothelial cell hypertrophy and hyperplasia (pink on capsule) typical of a spleen that has been manipulated to midline during surgical laparotomy.

Panel c; Shown is normal capsule histology (original magnification 20×) in a surgical sham rat in which the spleen was not moved (trichrome staining). Not the thin capsule and flattened mesothelial cell layer when compared to the image shown in b.

Panel d; Acetylcholine esterase staining of capsular mesothelial cells in a surgical sham rat. Note the flattened appearance of the mesothelial cells and strong positive staining for acetylcholine esterase. Original image magnification 20×.

Panel e; Acetylcholine esterase staining of capsular mesothelial cells in a rat in which the spleen had been moved to midline during surgery. Note the thickened capsular layer and hypertrophied appearance of the mesothelial cells. Positive staining for acetylcholine esterase is present but markedly less than that observed in control tissue. Original image magnification 20×.

Panel f; Acetylcholine esterase staining of capsular mesothelial cells in a surgical sham rat in which the esophagus was visualized but the vagal nerves left untouched without moving the spleen. Note the flattened appearance of the mesothelial cells and strong positive staining for acetylcholine esterase. Original image magnification 40×.

Panel g; Acetylcholine esterase staining of capsular mesothelial cells in a rat in which the vagal nerves were transected below the diaphragm without moving the spleen 14 days prior to tissue harvest. Note the absence of positive staining for acetylcholine esterase specifically in the surface mesothelial layer. Original image magnification 40×.

Panel h; Low power image of spleen described in panel f. Mesothelial cells staining positive for acetylcholine esterase can be observed as a necklace like appearance along the splenic capsule (indicated by arrows). Original magnification 10×.

Panel i; Low power image of spleen described in panel g. Note the lack of positive stained mesothelial cells on the splenic capsule. Acetylcholine esterase staining remains similar to control tissue in all other regions of the splenic parenchyma. Cells within and immediately below the capsule continue to stain positive for acetylcholine esterase. Original magnification 10×.