206 MANUAL OF HISTOLOGY. 



Bowman's capsule is composed of a structureless basement- 

 membrane surrounding each glomerulus. Upon the inner sur- 

 face of these capsules is a continuous layer of flat, epithelioid 

 cells, 1 which are continued over the glomerulus itself. 2 Occa- 

 sionally an epithelioid cell may be seen between the vessels of 

 the coil composing the glomerulus. 



Each capsule is pierced by two vessels, called, respectively, 

 afferent and efferent. The former enters the capsule and forms 



-D 



FIG. 92. Human kidney. Transverse section of cortical portion, showing the alternating arrangement 

 of pyramidal ray and cortical substance proper : A, A, pyramidal rays : B, convoluted tubule : C, elom- 

 erulus ; D, D, arterial vessels, x 55. 



the glomerulus, while the latter makes its exit close to the en- 

 trance of the former. The layer of epithelium above described 

 passes over from the inner surface of the capsule on to the 

 glomerulus about the points of entrance and exit just men- 

 tioned. On the opposite side, the capsule becomes continuous 

 with a convoluted tubule. To obtain specimens, the renal artery 

 of a fresh kidney should be injected with blue gelatine and then 

 placed in alcohol. Vertical and transverse sections of the cor- 

 tical substance may then be made. They should be stained in 

 carmine and examined in glycerine, or the artery may be in- 

 jected with absolute alcohol and the sections stained as above. 

 The epithelium of the tubules. The basement-membranes 

 of the convoluted tubules of the first order are in direct con- 

 tinuation with the basement-membranes of the capsules. Their 

 diameter averages 0.04 mm. The epithelium of these canals is 



1 Schweigger-Seidel : Die Nieren. Halle, 1865. Henle : Eingeweidelehre, p. 329. 

 Heidenhain : Zur anat. d. Nieren, in Schultze's Archiv, Bd. X., Hft. I. Mayer : His- 

 tology of the Kidney, Dis. Inaug., 1876. Also Bowman, Johnson, Frerichs, etc. 



2 Gerlach, Heidenhain. 



