22 CHAPTER XII 



KIDNEY. 



Kidney, of a small mammal for the general arrangement of 

 the tubules. T.S. Rat. ( p . 3, inj., s. 22 & 25, c. P., m. B.) (L) 

 Externally the thin and easily detached capsule rests upon the 

 cortex, the latter is readily distinguished from the medullary or 

 central portion of the organ by its pinker stain. The medulla 

 projects inwards as a conical papilla. The clear space around 

 the latter is the sinus of the kidney, lined by the pelvic expansion 

 of the ureter, a section of the latter will be found in the mass of 

 fat immediately outside. The cortex nearly meets around the 

 medullary part at this level of the organ. A little way above or 

 below the cortex would be continuous all round. Just outside 

 the pelvic membrane, find the Renal arteries and the larger thin- 

 walled veins. 



The medullary rays (pyramids of Ferrein) are clusters of renal 

 tubules which run outwards from the medulla into the cortex, 

 where they gradually disappear. The intervals between them 

 are filled by the convoluted tubes which exhibit the pink stain, 

 and amongst which note the bluer coloured glomemdi. 



Kidney -, for T.S. papilla. Rabbit, (p. 4., s. 17, c. P., m. B.) 

 (//) Find the papilla and recognise near its apex large collect- 

 ing tubes (ducts of Bellini), and if the section favours their 

 openings on the surface. If cut lengthways their dichotomous 

 divisions will be found. Between them (//) there is much 

 interstitial tissue, in which the capillaries are recognisable by 

 their thin endothelial coverings. Towards the cortex the 

 loops of Henle's tubes are to be found. 



