DEVELOPMENT OF THE ELASMOBRANCH LIVER 



361 



The lateral pouches merge into the pars hepatica mediana 

 anteriorly and the distinction between these parts in this region is 

 only possible through an examination of the tubule formation. 

 Posteriorly, however, the proximal portion or stalk of each poiich 

 is constricted and elongated to form the hinder part of a broad 

 short duct connecting the pars ductus of the median pouch with 

 the distal expanded portions of the lateral ones. This condition 

 is illustrated by the transverse section shown in figure 16. 



Pduct.TDed. ^ 





»ep.p. 



G.bl 



Fig. 16 Trans^verse section through the liver of an Acanthias embryo 15 mm. 

 long (H.E.C. 227). X 125. G.bl., gall bladder; L.hep.p., left hepatic pouch. 

 P.duct.med., pars ductus mediana; R.hep.p., right hepatic pouch. 



