24 



CYCLOPIA IN THE HUMAN EMBRYO. 



ovum it was found filled with a jelly-like fluid forming a type of magma described 

 in my paper upon this subject. Sections were cut of the fleshy chorion and it 

 was found that the wall is composed of a true chorionic membrane, villi, maternal 

 blood, fibrin, decidua, blood sinuses, and trophoblast, with an extensive infiltration 

 of leucocytes often accumulating in large masses or small abscesses. These layers 

 are not in any regular order, but are intermingled, and show various stages of 

 disintegration. The mesenchyme of the villi is fibrous, and many of these are 

 invaded by trophoblast cells as well as by leucocytes. The trophoblast also 

 invades the blood-clot, and maternal-blood sinuses are frequently found filled 

 either with trophoblast cells or with leucocytes. There are certain groups of tissue 

 in which the intermingling of 

 the trophoblast cells within the 

 fibrinoid substance appears, in 

 sections, very much like carti- 

 lage. Most of the decidua ad- 

 jacent to active trophoblast on 

 the tips of some of the villi has 

 the usual fibrinoid layer char- 

 acteristic of normal develop- 

 ment. It may be added that 

 the structures of the chorionic 

 membrane, as well as those of 

 the embryo, stain unusually 

 well, which indicates that the 

 tissues were active and alive at 

 the time of the abortion. 



After the embryo was re- 

 ceived it was photographed 

 from one side (plate 2, fig. 1), 

 and this record proved to be 



Very USeful in making Several FlG . o. Reconstruction of the head of embryo No. 201. X25. The 

 rorx-mct runt irme TVio ornKr-i'n outline of the head was obtained from a photograph, the brain and eyes 



J1 J from a plaster reconstruction, and the nerves were added from the sec- 



was then cut into serial sections 



50 mm. thick; finally, in order 



to study more carefully the structures within the head, a reconstruction of its 



external form, as well as of the form of the brain and the eye, was made in plaster of 



p:iris at a scale of 40 diameters. 



Most extensive changes have taken place within the embryo. The brain 

 is greatly deformed and is severed from the spinal cord through a growth of tissue 

 in the region of the medulla back of the deformed ear. In fact, a part of the 

 brain is included within the cap-like body on toil of the head. The spinal cord 

 begins again quite abruptly in the upper cervical region and ends with the same 

 abruptness in the upper lumbar region. At its lower end there is a curious fibrous 

 tumor measuring half the diameter of the cord. The cord, so far as it is developed, 



tions. C. H., cerebral hemisphere; M, midbrain; H, hindbrain; S, rudi- 

 mentary snout; V, fifth nerve; VI 11, eighth nerve; E, external ear. 



