Weibel-Palade bodies in endothelial cells of normal thoracic ducts and deep cervical lymphatics in rabbits.

The endothelial cells of normal thoracic ducts and deep cervical lymphatics were examined by electron microscopy using conventional staining methods and acid-phosphatase and ruthenium red (RR) reactions. The endothelial cells contained rod-shaped, circular and elliptical bodies of moderate density. The shape and structure of all these bodies were the same as those of the Weibel-Palade bodies (WPB) in the endothelial cells of blood vessels. They were usually found near the Golgi complex in groups, and the long axis of the rods paralleled the Golgi saccules. In addition, a peculiar vacuolated rod with a bulge was found adjacent to the WPB. Single coated vacuoles were occasionally located next to the WPB. Acid-phosphatase activity and RR positive material were not seen in the WPB and the vacuoles. Our observations suggest that the WPB have a close relationship, morphological as well as functional, to the Golgi complex in lymphatic endothelial cells.