FIG. 4.

Light micrographs of serial sections of the pulmonary ligament. The submesothelial layer consists of fibrous connective tissue, which is occasionally discontinuous due to interruptions by stomata. The stomata are lined with low-molecular weight cytokeratin CAM5.2(-), D2-40(+), and CD31(+) lymphatic endothelial cells (A, B, and C; hematoxylin and eosin staining, objective 20X) (D, E and F, immunohistochemistry, low-molecular weight cytokeratin CAM5.2, D2-40, and CD31, respectively, objective 20X). Asterisks indicate submesothelial lymphatic lumens. The scale bars indicate 20 μm. A color version of this figure is available in the online article at www.liebertpub.com/lrb