A CONTEIBUTION TO OUE KNOWLEDGE OF THE 



EARLIEST KNOWN STAGES OF PLACENTATION 



AND EMBEYONIC DEVELOPMENT IN MAN. 



BY 



MAXIMILIAN HERZOG. 



From the Laboratory of Pathology of the Michael Reese Hospital, 



Chicago, Illinois. 



With 30 Illustrations. 



CONTENTS. 



P^GE 



Introductory Remarks 361 



History of the Case from which the Ovum Came 367 



General Description of the Ovum 371 



Description of the Embryo 373 



Description of Chorion and Decidua 376 



Nomenclature 376 



The General Position of the Ovum and its Mode of Entrance into 



the Decidua 379 



Exocoelom and Chorion Mesoderm 385 



The Trophoblast and its Syncytium 387 



The Border Zone 391 



The Decidua 394 



Summary 398 



List of Illustrations 



Introductory Eemarks. 



The most important original contribution to our knowledge of 

 the earliest stages of human placentation was made less than ten 

 years ago bj Peters, whose monograph, "Ueber die Einbettung des 

 menschlichen Eies," Wien, 1899, is well known to every student of 

 the subject. 



The present author, a nuniber of years ago, became interested in 

 human placentation, primarily in connection with the morbid an- 

 atomy and histopathology of ectopic gestation, and he has for 

 years, as a matter of routine, searched for very young human ova 

 in every uterus and Fallopian tube which fell into his hands, either 



The American Journal of Anatomy. — Vol. IX, No. 3. 



