THE HISTOGENESIS OF THE SELACHIAN LIVER 



RICHARD E. SCAMMON 



Institute of Anatomy, University of Minnesota 



FORTY-FIVE FIGURES (SEVEN PLATES) 



CONTENTS 



Introduction 245 



Development of the hepatic cylinders 246 



1. Literature 246 



2. Early development 249 



3. The process of anastomosis 253 



4. Later development 258 



a. Growth of the hepatic network 258 



b. Changes in size and structure of the hepatic cylinders 261 



5. Development of the hepatic tubules in different forms of selachians. . 266 



Development of the minor rami of the hepatic ducts 269 



Development of the hepatic mesenchyma 272 



History of the hepatic sinusoids 282 



Summary 294 



Bibliography 299 



INTRODUCTION 



The structure of the adult selachian liver is far removed from 

 that type which is generally considered characteristic of the 

 organ in ertebrates. This variance from the common verte- 

 brate type is seen in the great accumulation of fat in the hepatic 

 cells, in the comparatively slight d-evelopment of the bile duct 

 system and in the absence of lobulation of the kind generally 

 found in higher vertebrates.^ However, these pecularities which 



^ The histology of the adult elasmobranch liver was first briefly described by 

 Leydig ('51) from observations on Chimaera. He published a more complete 

 account dealing with several forms of selachians in 1853. Later descriptions of 

 the general histology of the adult liver have been given by Shore and Jones ('89), 

 Pilliet ('90), and Holm ('97). Deflandre ('05) has investigated the fat content 

 of the hepatic cells, and Monti ('98) has studied the bile capillaries by the Golgi 

 method. 



245 



THE AMERICAN JOURNAL OP ANATOMY, VOL. 17, NO. 3 

 MARCH, 1915 



