116 WOOLFIAN BODIES. 



cular, and of a granulated arrangement ; it constitutes the cortical 

 portion. 



The cortical substance^ consists of a number of tortuous tubes of 

 Ferrein^ in which the urine is first formed, and between whose walls 

 are a number of small bodies called the corpuscles of Malpighi ; 

 these are composed principally of vessels. 



The medullary cone of Malpighi,^ is capable of subdivision into 

 small pyramids of Ferrein, and each pyramid of Ferrein will be 

 found to consist of a number of straight tubes of Bellini, into which 

 the tortuous tubes of Ferrein empty. 



The apex of each cone is called papilla renalis, and in the centre 

 of each papilla is a slight depression ceXled foveola. 



Each papilla is surrounded by a small membranous cup called 

 irfu?uHbulum,* into which the urine is first received as it oozes 

 from the orifices of the papillce. Four or five of these infundibula 

 join to form a common trunk called calyx,^ and the junction of about 

 three calyces form a common cavity called the pelvis,^ which is of 

 a conoidal shape, and from which proceeds the ureter ^ the excretory 

 tube of the kidney which conveys the urine to the bladder. 



The ureter^ is a cylindrical tube of the size of a quill, with thin, 

 white, extensible walls. Crossing in its descent the iliac artery, it 

 enters the inferior fundus of the bladder very obliquely, and opens 

 by a very small orifice. It consists of two coats ; the external of 

 which is fibrous, and the internal is mucous. The structure of the 

 calyces and infundibula is the same. 



SUPRA-RENAL CAPSULES. 



The capsulce renales^ (fig, 99), are two small borders, varying 

 much in size, placed one on each side just above the kidney, and 

 reposing on its upper extremity. They are of a light brown colour, 

 and surrounded by condensed cellular tissue. In foetal and youthful 

 life they are much larger than in adult life, and hence it is supposed 

 that the use is confined to that period of life, as in the case of the 

 thymus gland. They are of a triangular or semicircular shape, the 

 base being excavated where it is adjusted to the kidney. Having 

 no secretion they of course have no duct. 



They are supplied by the capsular artery, a branch of the renal 

 or aorta. 



WOOLFIAN BODIES. 



These structures exist only until the sixth month of foetal life. 

 Before this period they conceal the kidney and renal capsule. They 

 consist of tubes which empty into the sinus uro-genitalis, a duct 

 peculiar to fcetal life. 



