To the Editor:We read with great interest thearticle by Gao and his colleagues proposing anew schema and hypothesis regarding pleural fluidturnover.In the proposed hypothesis,the visceralpleura possesses a more active role in humans thanwhat was believed.The authors support the notionthat in humans the pulmonary lymphatic vesselsoriginate directly from the mesothelium of thevisceral pleura and that it has an effect on bothinfiltration and reabsorption of pleural fluid in humanbeings.However,there are some points that are worthcommenting.Should the lymphatic vessels originatefrom the visceral mesothelium,they would form To the Editor: We read with great interest the article by Gao and his colleagues proposing anew schema and hypothesis regarding pleural fluid turnover. In the proposed hypothesis, the visceralpleura possesses a more active role in humans thanwhat was. The authors support the notion in the humans the pulmonary lymphatic vesselsoriginate directly from the mesothelium of thevisceral pleura and that it has an effect on both infiltration and reabsorption of pleural fluid in humanbeings. Host, there are some points that are worth commenting.Should the lymphatic vessels originatefrom the visceral mesothelium, they would form