DEVELOPMENT OF LIVER AND PANCREAS 235 



an 11 nim. embryo the right duct is distinctly divided into lateral 

 and medial rami. A short cystic duct is attached to the caudal 

 end of the lateral ramus and on its ventral side. In an embryo 

 somewhat less than 13 mm. long the same arrangement of a 

 short common duct and right and left hepatic ducts is present. 

 The right duct is divided into the medial and lateral rami. The 

 cystic duct here projects somewhat to the left and dorsal ward 

 connecting as before with the right lateral ramus. 



In a graphic reconstruction of a 13 mm. embryo (fig. 18) 

 the right hepatic duct is divided into lateral and dorso-medial 

 rami. The short cystic duct extends upward and opens into the 



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D/15. 



R/d- 



.ms 



Fig. 20 Anterior view of a reconstruction of the lumina of hepatic ducts 

 and gall-bladder of a 9 mm. embryo. X 100. D.h.d., right hepatic duct; D.h.s., 

 left hepatic duct; G.b., gall bladder; R.l.d., right lateral ramus; R.l.s., left lateral 

 ramus; R.m.d., right medial ramus; R.m.s., left medial ramus. 



right lateral ramus. A short lateral branch is the only other 

 division of the right lateral ramus. The dorso-medial branch 

 shortly breaks up into trabeculae. The left duct is also divided 

 into rami. The differentiation of hepatic ducts from trabeculae 

 is now clearer as the epithelium of the former is columnar in 

 type. 



In figure 19 from an embryo less than 1 mm. longer than the 

 above, the formation of ducts is seen to have continued. The 

 right hepatic duct is divided into lateral and medial rami, each 

 of which is further divided into dorsal and ventral branches. 

 The same holds true in a general way for the left hepatic duct 

 and its divisions. 



