UTERINE BLOOD FLOW 



I 591 



Vertebral plexus +0 brain 



anas+omosi 

 por ro-ovaric 

 «<evtra 



fig. 5. The uterine drainage in ad- 

 vanced first pregnancy, with predomi- 

 nantly high fundal drainage through the 

 pampiniform plexuses and ovarian veins 

 toward the kidneys, and through visceral 

 and segmental communications, toward 

 the portal circulation, vertebral plexus, 

 and brain. [Reprinted by permission 

 from Bieniarz (31).] 



fig. 6. Anterior and posterior 

 view of the uterus with the venous 

 vascular patterns visible during 

 cesarean section and with regions 

 of placental location. U, upper; 

 M, middle; L, lower portion of 

 uterus. [Reprinted by permission 

 from Bieniarz (31).] 



Annul os view 



shunt.) A more comprehensive discussion of this 

 subject will be found elsewhere [Reynolds (198)]. It 

 should be noted that there is no logical reason why 

 either the ovarian vein hypothesis or the placental 

 ischemia hypothesis as an etiological factor excludes 

 the other. 



The above assertion of morphological and clinical 

 facts makes it clear that the change and distribution of 

 blood flow within and from the pregnant uterus is 

 governed in part by the site of placental implantation, 

 in part by the change in size of the uterus, and in part 

 by the increase in quantity of functional uterine 



POSIlStOK VIEW 



tissue during pregnancy. Local or regional blood flow 

 is associated with the supply of blood to the uterine 

 tissues and especially to the placenta. 



COMPARATIVE ANATOMY OF THE PLACENTA 



As with the above discussion of the uterus, it is 

 necessary to recognize that there is a wide array of 

 placental forms. Although Mossman (158) has de- 

 scribed these forms and noted their arrangements 

 throughout the several orders of mammals, insufficient 



