THE DEVELOPMENT OF THE SUPRAPERICARDIAL 



(POSTBRANCHIAL, ULTIMOBRANCHIAL)) 



BODY IN SQUALUS ACANTHIAS 



WALTER E. CAMP 



Institute of Anatomy, University of Minnesota 



TWENTY-NINE FIGURES (TWO PLATES) 



CONTENTS 



Introduction 369 



Literature 370 



Topography and morphology 376 



Histology and histogenesis 389 



Angiogenesis 398 



Discussion 402 



Summary 408 



Bibliography 410 



INTRODUCTION 



Much attention has been given in recent years to a study of 

 the derivatives of the caudal portion of the pharynx in the higher 

 vertebrates, particularly in mammals. Of these derivatives the 

 ultimobranchial or postbranchial body has been perhaps the 

 subject of the most discussion and has given rise to the most 

 diverse opinions as to its significance and fate. From a review 

 of the literature it is obvious that most investigators consider 

 the ultimobranchial body homologous with the suprapericardial 

 body of selachians. In this group little work has been done on 

 the suprapericardial body since the original communication in 

 1885 of its discoverer, van Bemmelen. Owing to the absence 

 of any complete description of the gland in a single form of the 

 lower vertebrates, and because of the singular position it occu- 

 pies among glands when classified according to form, it was 

 thought that a detailed study of its development and structure 

 in a single form (Acanthias) would be desirable. It is hoped 



369 



