64 G. CARL HUBER 



readily accomplished than in those obtained during the preceding 

 day. Of the 59 vesicles of this stage obtained, many show ex- 

 cellent fixation. The thin wall of the vesicle is no longer so prone 

 to fold as in the preceding stage, and does not readily retract 

 from the uterine epithelium or mucosa, no doubt owing to a 

 distinct adhesion of vesicle wall to the maternal tissue. It is 

 difficult, however, so to orient the vesicles as to obtain sections 

 of a desired plane. The general position of a given vesicle is 

 readily determined, since the enlargement of the uterus marking 

 its location is very evident. The vesicles are located in approx- 

 imately cylindrical cavities, known as decidual crypts, which 

 are directed toward the antimesometrial border. 



These decidual crypts communicate with the lumen of the 

 uterus, which lies eccentric and nearer the mesometrial border, 

 by means of funnel-shaped openings. The decidual crypts or 

 cavities are still lined with uterine epithelium, though this is 

 now much flattened in the immediate vicinity of the vesicle 

 and may be found in part separated from the mucosa of this 

 region. The vesicles are now so placed that in all of them, the 

 thicker portion, the floor of the blastodermic vesicles of younger 

 stages or region of the germinal disc, is directed toward the 

 mesometrial border, thus toward the still patent lumen of the 

 uterus, while the roof of the vesicles is directed toward the an- 

 timesometrial border, thus toward the bottoms of the decidual 

 crypts. The general direction of the decidual crypts is in the 

 main at right angle to the long axis of the uterine horn, and 

 directed from the mesometrial to the antimesometrial border. 

 They may deviate, however, from the general direction at 

 various angles and in almost any direction. The decidual crypts 

 as seen in cross section do not as a rule present a circular outline, 

 but appear as slightly compressed from side to side, having thus 

 an oval outline as seen in cross section, with the long axis of this 

 oval space as seen in cross section approximately parallel to the 

 long axis of the uterine horn. Since the direction of the decidual 

 crypts can in uncut material be only approximated, the obtaining 

 of sections cut in a desired plane becomes largely a matter of 

 chance. In a large number of my preparations the contained 



