198 



THE ESSENTIALS OF HISTOLOGY. 



arterial arches, which almost immediately break up into pencils of fine 

 straight arterioles running in groups between the straight tubules of 

 the medulla. These arterioles gradually break up into a capillary net- 



FIG. 232. SECTION ACROSS A PAPILLA OF THE KIDNEY. (Cadiat.) 

 a, large collecting tubes (ducts of Bellini) ; b, c, d, tubules of Heiile ; e, f, blood-capilLaries. 



work with elongated meshes which pervades the medulla (fig. 233, /), 

 and which terminates in a plexus of somewhat larger venous capillaries 

 in the papillae. From these and from the other capillaries the veins 

 collect the blood, and pass, accompanying the straight arterioles, into 

 the venous arches between the cortex and medulla. The groups of 

 small arteries and veins (wsa recta) in the part of the medulla nearest 

 the cortex alternate with groups of the uriniferous tubules, and this 

 arrangement confers a striated aspect upon this portion of the medulla 

 (boundary zone, see fig. 234, g). 



The efferent vessels of those glomeruli which are situated nearest 

 to the medulla may also break up into pencils of fine vessels (false 

 arterm rectce) and join the capillary network of the medulla (fig. 233, d). 



Between the uriniferous tubules, and supporting the blood-vessels^ 

 is a certain amount of connective tissue (fig. 232), within which are 

 cleft-like spaces from which the lymphatics of the organ originate. 



