PATHOLOGIC OVA, ALBINO RAT 379 
decidual crypts are relatively shallow when compared with those 
of normal uteri of similar stages with normal ova. The uterine 
mucosa of the two rats under discussion does not appear to have 
reacted in a normal manner. In these preparations, attention is 
especially drawn to the presence of maternal blood with numerous 
phagocytic leucocytes found in relation with the ova, a condition 
never observed in normal development of ova and uterine mu- 
cosa. In A and B, figure 7, the red and white blood cells with 
granular detritus may be observed as found in relation with the 
respective vesicles, these presenting essentially the same appear- 
ances as do the other six ova obtained from these two rats; the 
one figured having been more favorably cut than any of the 
others. The appearances presented in these two rats are inter- 
preted as showing a probable degeneration of the eight ova, and 
probably complete dissolution and removal. The vesicles appear 
to have developed normally to the stage at which they were ob- 
tained. As a result, however, of pathologic condition of the 
uterine mucosa, maternal blood, especially leucocytes, have 
entered the lumen of the uterus, the leucocytes being destined 
to play the réle of phagocytes. In normal development of the 
albino rat, maternal blood does not enter the lumen of the uterus 
—decidual erypts—until after the uterine epithelium has become 
detached from the mucosa of the wall of the decidual crypt, in 
the region of lodgment of the enclosed ovum. Normally, very 
few leucocytes are met with in the lumen of the uterus, even in 
later stages of development, stages in which maternal red blood 
cells are met with in the decidual crypts. After experience had 
accumulated, uterine tubes supposed to contain developmental 
stages aging from the fourth to the sixth day, which on examina- 
tion revealed blood and especially leucocytes in the lumen of the 
uterus, were regarded as not favorable specimens for finding ova. 
In a number of such uteri, cut completely in serial sections, no 
ova were found. It is possible that, owing to phagocytic action 
of the leucocytes present, the ova may have been completely 
removed prior to killing and fixing the tissues. In such condition, 
it would seem to me as pertinent to speak of faulty implanta- 
tion, due to abnormal uterine mucosa. It seems to me signifi- 
JOURNAL OF MORPHOLOGY, VOL. 26, NO. 2 
