PATHOLOGIC OVA, ALBINO RAT 141 



b. Such in which a single abnormal or pathologic ovum is 

 found in the same uterus along with an average number of 

 normally developed ova. 



When all the ova in a given uterus show abnormality, the 

 presumption seems warranted that the underlying cause of the 

 abnormality is to be sought in an altered or pathologic condition 

 of the uterine mucosa. In the instances observed, the presence 

 of maternal blood with many phagocytic leucocytes was noted 

 in the lumen of the uterus, adhering to and surrounding the ova. 

 From the study of sections of the uteri of an appreciable number 

 of albino rats, in which insemination and supposedly semination 

 seemed normal, but in which on complete serial sectioning of the 

 uterine tubes no ova were found, but in the lumen of the uterine 

 tubes of which the presence of maternal blood and phagocytic 

 leucocytes was noted, the conclusion seems warranted that 

 death and complete absorption of ova, after a given stage of nor- 

 mal development has been reached, may occur. In such cases, 

 one may with propriety speak of faulty implantation, due to 

 altered or pathologic condition of the uterine mucosa, even in 

 cases where no actual implantation would have occurred in cor- 

 responding normal stages. In the two rats (Nos. 91 and 104) 

 in which this condition was observed, the decidual crypts were 

 shallow and not developed to the extent normal for the respec- 

 tive stages, evidencing the abnormal condition of the mucosa. 



In cases in which a single abnormal or pathologic ovum is 

 found in the uterus along with several normal ova, the pre- 

 sumption seems justified that the underlying cause responsible 

 for the abnormal development is to be sought in the ovum itself, 

 and not in its environs. 



Abnormal developmental stages, interpreted as due to irregu- 

 lar or retarded segmentation, irregular or abnormal segmenta- 

 tion cavity formation, and retarded development of the ecto- 

 dermal node and primary embryonic ectoderm, where only a 

 single ovum shows abnormal development in a uterus contain- 

 ing the average number of ova presenting normal development, 

 are difficult to explain on the assumption that extraneous in- 

 fluences affecting a single ovum are operative. Practically all 



