THE EXCRETORY AND REPRODUCTIVE SYSTEMS. 



175 



enlarges, forming the pelvis, into which projects the renal 

 papilla (Fig. 84). This is better demonstrated in a 

 transverse section. 



The substance of the kid- 

 ney is composed of an outer 

 cortical layer, about a half 

 centimeter thick, and an 

 inner medullary substance 

 adjacent to the pelvis, and 

 projecting into the latter in 

 the form of a papilla. In 

 the cortical substance are 

 hundreds of Malpighian 

 bodies, each composed of a 

 ball of capillaries (Fig. 84) 

 enveloped by the invagin- 

 ated enlarged extremity of 

 a tubule which carries away 

 the urine by a tortuous 

 course to the papilla (Fig. 

 85). In the Malpighian 

 bodies the water and other 

 mineral substances of the 

 urine are extracted from the 

 blood by means of the epi- 

 thelial cells forming the 

 inner wall of the capsule of 

 Bowman. These urinary 

 products pass through the 

 proximal convoluted tubule 



cl 



FIG. 83. VENTRAL ASPECT OF FE- 

 MALE URINO-GENITAL SYSTEM 

 WITH THE BLADDER PULLED TO 

 ONE SIDE. 



a, Entrance of the urethra into the 

 vestibule; ao, aorta; bl, bladder; 

 cl, clitoris; en, cornu or horn of 

 the uterus ; ft, Fallopian tube, the 

 left one is cut off ; fm, fimbriated 

 extremity of the Fallopian tube ; 

 kd, kidney; /, ovarian ligament; 

 crv, ovary; ra, renal artery; rv, 

 renal vein ; re, rectum ; ur, ureter ; 

 ut, body of the uterus; uth, ure- 

 thra; ye, vena cava; vg, vagina; 

 vs, vestibule. 



and the loop of Henle to the 



distal convoluted tubule, where they are mingled with the 

 urea extracted from the blood by the columnar epithelial 

 cells of the tubule. From this point the excretions flow 



