Ultrastructure of the crocodile kidney (Crocodylus acutus) with special reference to electrolyte and fluid transport

The study of the ultrastructure of the kidney tubules of the crocodile was made to compare the cellular structure with the capacity for electrolyte resorption and the ability to create an osmotic gradient across the tubular wall. The crocodile tubular cells were found to differ from the mammalian tubular cells in that they do not have basal infoldings, but instead have open lateral spaces between the cells, similar in many aspects to those found in the mammalian gallbladder. The physiological role of these lateral spaces in solute and fluid transfer is discussed.