Structure and Function of the Peritoneal Funnels of the Frog, Rana pipiens

Abstract

Heidenhain found no trace of peritoneal funnels in the frog's kidney. Spengel first saw these funnels in such forms as R. ternporaria, B. cinereus, D. pictus, and Bombinator. He claimed that in the Coecilia and Urodela there was a connection between these funnels and the malpighian bodies but that in B. cinereus he found a connection with the fourth section of the uriniferous tubule. Simultaneously but independently Meyer, using the silver nitrate method, counted 195 openings on the adult frog's kidney. Nuss-baum reported that in larval anura the connections were between the peritoneal tubes and the neck of the malpighian body while this connection was shifted, in the adult anura, to the renal veins. He showed this renal vein connection more conclusively in R. fusca, R. esculenta, B. calamita, and A. obstetricans. In the same year Hoffman stated that these tubules in the adult anura end blindly. Ecker claimed that the funnels were very difficult to find; that they did not connect any part of the uriniferous tubule with the body cavity; and that their superficial terminations had no cilia. Marshall and Bles described the embryonic formation of these funnels and tubes and showed that in R. temporatia they lose their early connections with the malpighian bodies and uriniferous tubules and finally empty into renal veins. Farrington injected carmine into the renal portal veins and found it emerging from the peritoneal funnels but he did not indicate why blood corpuscles were not likewise liberated into the body cavity of untreated frogs. He did state that in the Urodela these tubes opened into the uriniferous tubules but in both R. catesbiana and R. virescens they opened into branches of the renal portal veins.