646 STROMA OF THE KIDNEY. [BOOK n. 



398. The connective-tissue which binds together the tubules 

 and blood vessels is exceedingly scanty. Some small amount enters 

 with the blood vessels, and is continued on along their larger 

 branches, but in the cortex the " stroma " consists of hardly more 

 than the basement membranes of the tubules, with a few connective- 

 tissue corpuscles imbedded in a scanty homogeneous not fibrillated 

 matrix lying between them ; around the capsules this stroma is 

 rather more abundant than elsewhere, and here is sometimes 

 fibrillated. In the pyramids, especially at their lower parts, a 

 larger amount of a similar homogeneous matrix, containing con- 

 nective-tissue corpuscles, is found between the tubules ; and since 

 here the basement membrane of the tubule is fused with this 

 stroma, the tubule appears as a tubular cavity hollowed out of 

 the matrix or stroma and lined with epithelium. 



The whole kidney is surrounded by a capsule, consisting of 

 ordinary connective-tissue and continuous at the hilus with the 

 connective-tissue forming the outer walls of the pelvis and ureter. 

 This capsule may after death be peeled off, and slender processes 

 of connective-tissue with some blood vessels passing from the 

 capsule into the cortex are then disclosed. 



In the scanty stroma are numerous lymph-spaces, the lymph 

 from these being collected into lymphatic vessels which in part 

 leave the kidney by the hilus together with the blood vessels, and 

 in part run in the capsule and leave the kidney on its convex 

 surface. The capsule is described as separable into two layers, 

 and the lymphatic vessels run chiefly between these layers. 



399. As the renal artery passes to the kidney it is invested 

 by a number of (twenty or less, in the dog a dozen or more) 

 nerves, arranged in a plexus, the renal plexus. The nerves are 

 composed partly of medullated fibres of very different sizes and 

 partly of non-medullated fibres; numerous small ganglia, differing 

 however very much in size, are scattered over the plexus. 



The nerves thus forming the renal plexus come chiefly from the 

 great solar plexus, and appear to be more immediately connected 

 with the part of that plexus which is called the semilunar ganglion. 

 The plexus is therefore indirectly connected with the nerves 

 entering into the solar plexus, such as the right vagus and the 

 abdominal splanchnic nerves, great and small. Besides this the 

 splanchnic nerves appear to send filaments directly to the renal 

 plexus ; filaments have also been traced to the left kidney from 

 the left vagus (which does not join the solar plexus), and it is 

 contended that filaments from the right vagus also make their 

 way direct to the right kidney, without distinctly communicating 

 with the solar plexus. 



As we shall see there is experimental evidence that, in the 

 dog, nerve fibres from the anterior roots of the llth, 12th and 

 13th dorsal spinal nerves and even a few fibres from still lower 

 nerves find their way to the renal plexus and so to the kidney. 



