Innervation of Kidney of Toadfish. ∗

Abstract

While an intimate relation of nerve fibers to the epithelium of the renal tubules has been reported most strikingly by Smirnow, 1 the finer nervous mechanism of the kidney is still in doubt. The extrinsic nervous control of urinary secretion has been variously interpreted (Bieter, 2 Kuntz 3 ), it being particularly difficult to separate results arising from vasomotor changes from strictly secretory phenomena. In the opinion of several investigators (for most recent summary of literature see Marshall and Grafflin 4 ), at least the proximal convoluted segment of the renal tubule has important secretory functions. The aglomerular kidney of the toadfish (Opsanus tau) has afforded unusually favorable material for studying the secretory processes that may be carried on by the tubular epithelium since there are no glomeruli to complicate the process. The terminal portion consists only of a blind tubule with the histological characteristics of the proximal convoluted tubule of higher animals (Edwards 5 ). Bieter 6 showed that in this animal the secretory pressure of urine as registered in the ureters can be greater than the blood pressure in the dorsal aorta. This phenomena together with the action of diuretics on the urinary output (Bieter 7 ) and on the cytological structure of the tubular epithelium (Defrise 8 ), and other related problems, naturally bring up the question of the nerve supply to these aglomerular tubules,

Dr. Bieter, having a supply of living toadfish for additional studies on the action of various drugs on kidney function, suggested this study and generously supplied an abundance of fresh material.

From a study of similar work on other animals, a variety of techniques were selected, including intra-vitam methylene blue in a buffer solution so that the pH could be changed as described by Hirt, 9 modified Bielschowsky stain (Oertel, 10 Rogers 11 ), gold chloride, silver-pyridine (Ranson 12 ), and various stains for connective tissue and muscle fibers.