THE HISTOGENESIS OF THE PINEAL BODY OF 



THE SHEEP 



H. E. JORDAN 



From the Anatomical Laboratory of the University of Virginia 



ELEVEN FIGURES * 



CONTENTS 



Introduction 249 



Material and methods 251 



The 5 cm. stage of development 252 



The 10 cm. stage of development 252 



The 11 cm. stage of development 253 



The 15 cm. stage of development 253 



The 17 cm. stage of development 254 



The 21 cm. stage of development 254 



The pineal body at term 255 



The pineal body of lambs 256 



The pineal body of yearling sheep 258 



The pineal body of old sheep 259 



General 259 



Review of literature 261 



Nature of cytoplasmic granules 262 



Conclusions and discussion 266 



Summary 267 



Literature cited 269 



INTRODUCTION 



This investigation is the outcome of a search for histologic 

 evidence indicating a physiologic function for the pineal organ of 

 mammals. In this search a variety of animals were examined, 

 including cat, dog, guinea-pig, rabbit, rat, opossum, calf, sheep 

 and man. In general the macroscopic findings in corpora pine- 

 aUa of adult mammals seem to negative the presumption of func- 

 tional importance. In the first five animals above mentioned the 

 body is very small; and the observation that in very large dogs, 

 for instance, it is no larger than in small dogs or that in horses it is 



THE AMERICAN JOURNATj OF ANATOMY, VOL. 12, NO. 3 

 NOVEMBER, 1911 



249 



