Boykin S L, Braun E J
Department of Physiology, College of Medicine, University of Arizona, Tucson 85724.
J Morphol. 1993 Jun;216(3):259-69. doi: 10.1002/jmor.1052160303.
The avian kidney contains a population of nephrons with and without loops of Henle. How the collecting ducts of this heterogeneous population of nephrons merge to exit as single ducts from the medullary cones has been uncertain. The results of this study show that the collecting duct tree begins with the coalescence of the distal tubules of pairs of loopless nephrons. These primary collecting ducts receive output from only loopless nephrons. Primary collecting ducts fuse in pairs and become secondary collecting ducts. They receive the distal tubules of transition nephrons. Pairs of secondary collecting ducts fuse and become tertiary collecting ducts. Tertiary collecting ducts receive the distal tubules of looped nephrons. Thus, the fluid from all nephron types comingles as it passes through the medullary cone. The results of this study also show that the anatomical arrangement of medullary cones does not permit the output from one medullary cone to enter a second medullary cone. Thus, all the medullary cones function as parallel units. This anatomical organization of the avian kidney affects its ability to produce a urine hyperosmotic to the plasma.
禽肾包含有髓袢和无髓袢的肾单位群体。这种异质性肾单位群体的集合管如何合并并作为单一管道从髓质锥体排出一直不确定。本研究结果表明，集合管树始于无髓袢肾单位对的远端小管的融合。这些初级集合管仅接收无髓袢肾单位的输出。初级集合管成对融合并成为次级集合管。它们接收过渡肾单位的远端小管。成对的次级集合管融合并成为三级集合管。三级集合管接收有髓袢肾单位的远端小管。因此，来自所有类型肾单位的液体在通过髓质锥体时混合在一起。本研究结果还表明，髓质锥体的解剖结构不允许一个髓质锥体的输出进入第二个髓质锥体。因此，所有髓质锥体都作为平行单元发挥作用。禽肾的这种解剖结构影响其产生比血浆渗透压更高的尿液的能力。
