The transendothelial passage in the absorbing peripheral lymphatic vessel of the rodent diaphragm.

The absorbing peripheral lymphatic vessels of rat (Wistar/Kyoto) and gerbil (Meriones unguiculatus) diaphragms were observed with SEM, TEM and three-dimensional models under normal conditions, after experimental hemorrhage and after abdominal injection of China ink and latex polystyrene particles. Superficial and deep lymphatic vessels were noted and their ultrastructural characteristics showed an endothelial wall lacking a continuous basal lamina. Moreover, "intraendothelial channels" which are dynamic, fundamental pathways for lumen migration into the lymphatic vessel for fluids, China ink and latex polystyrene particles, were also demonstrated. Concerning the transendothelial passage of the autologous erythrocytes after their migration through the stomata and submesothelium connective channel, it was observed that this passage occurs by means of a "transcellular pathway". This consists of a "migratory pore" independent from the intercellular junctions, which is formed by an active process following a probable immunological response or cellular interaction between the erythrocyte and the endothelial cell.