322 HISTOLOGY 



The glomerulus often appears lobed, due to the arrangement of its vascular 

 loops. The capillaries unite to form a single efferent vessel which is smaller 

 in diameter than the afferent vessel; thus the pressure within the glomeru- 

 lus is increased. The entire glomerulus is regarded as arterial. On leav- 

 ing it, the efferent vessel divides into small branches. These spread 

 among the convoluted and straight tubules of the cortex, and some con- 

 tinue into the medulla. The latter is supplied also by straight branches (ar- 

 teriolcB recta) from the interlobular, efferent and arciform arteries, as shown 



in Fig. 317. The veins of the medulla begin 

 Renal around the papillae, and as venula recta empty 



corpuscle. f ... _,, ... 



into the arcnorm veins. The cortical veins are 

 the interlobular vessels which are beside the 

 corresponding arteries. They arise from con- 

 verging veins in the renal capsule, which on 

 surface view form stellate figures (vence 

 stellata). The interlobular veins drain the 

 capillaries of the cortex, but have no direct 

 relation with the glomeruli. Interlobar -veins 

 follow the arteries, passing out from the hilus of 

 the kidney^over the ventral surface of the renal 



Unmferous tubules. * 



FIG. 320. FROM THE KIDNEY OF A P e l vls - 



MOUSE. GOLGI PREPARATION. Lymphatic vessels are said to occur within 

 the cortex and to follow the blood vessels out at 



the hilus. The cortical lymphatics also pass through the tunica fibrosa 

 to connect with a network in the adipose capsule. They proceed to 

 neighboring lymph glands. 



The nerves are medullated and non-medullated. There is a sym- 

 pathetic plexus at the hilus associated with small ganglia, and from it 

 interlacing nerves extend into the kidney around the vessels (Fig. 320). 

 Fine branches supply the epithelial cells, especially those of the convoluted 

 tubules. They form plexuses beneath and above the basement membrane, 

 and have free intercellular endings. 



RENAL PELVIS AND URETER. 



The renal pelvis and ureter both consist of a mucosa (and submucosa), 

 muscularis and adventitia (Fig. 321). The mucosa includes the epithelium 

 and tunica propria, the latter blending with the submucosa. In sections 

 the epithelium resembles that of the moderately contracted bladder (Fig. 

 322), and its cells when found detached in urine are not distinguishable 

 from bladder cells. The epithelium is stratified but consists of few layers. 

 The basal cells are rounded, those of the middle layer are club shaped or 

 conical with rounded ends, and the outer cells are columnar, cuboidal, 



