Intraluminal latex injection: An aid to the histological identification of renal tubules

Intraluminal injections of neoprene or latex have been used for several years as a means of determining the exact site of fluid collection along the renal tubule during micropuncture experiments. After the tubules have been injected, it is the usual practice to excise a small wedge of tissue surrounding the injected tubule or nephron and then treat the tissue with concentrated hydrochloric acid to effect solidification of the latex column and maceration of the surrounding tissue. The latex “cast” is then dissected free of the macerated tissue and appropriate measurements are taken from the anatomic point of reference (glomerulus for proximal tubule, macula densa for distal tubule) to the site of puncture. The location of the puncture site can then be expressed in terms of its relative distance from the beginning of the proximal or distal convoluted tubule. However, since the epithelium of the injected tubule undergoes maceration in the hydrochloric acid, direct and parallel histological observations at the site of puncture have not been possible as a rule. The present report describes the use of intraluminal latex injections to aid in the histological identification and characterization of the epithelium at the exact site of micropuncture. The technique can also be used to aid in the positive identification of the epithelium within other segments of the same tubule that are more distant from the site of puncture. Use of this technique permits the simultaneous evaluation of function and structure under identical physiological conditions via an analysis of the composition of tubule fluid and an examination of cellular structure with light and electron microscopy.