276 STUDIES ON PATHOLOGIC OVA. 



Careful examination of the serial sections, generously made in the Carnegie 

 Laboratory of Embryology, fails to reveal any remnant of the body of the embryo 

 except, perhaps, a small nodule shown above the X in figure 172 (plate 16, Chap. 

 XI). Yet, according to the menstrual age, the embryo should be 10 to 12 mm. 

 long. The appearance of this nodule suggests that it may be a remnant of the 

 primitive streak in spite of its deep location, although it may also be a rudiment 

 of the allantois. The yolk-sac is large and invaginated and its size out of all 

 proportion to that of the rest of the embryonic rudiment. In the latter there is 

 a rather large mass of cells containing a space which, I take it, represents the 

 amniotic cavity. An examination of this cavity and of the surrounding cells 

 suggests that it resulted from splitting or cavitation, as is the case in bats and as 

 is assumed also for man by Eternod and others. This cavity may have resulted 

 from dissolution of the cells in situ, and if in fact it represents the early amniotic 

 cavity, then, whatever its genesis, it is probable that it was not formed in conse- 

 quence of folding. 



It would seem, then, that we have here a conceptus in which the process of 

 development of the embryo itself was inhibited very early but that the yolk-sac 

 and the chorion continued to grow for some time. 



Aside from showing a probable and hitherto unobserved stage in the forma- 

 tion of the amniotic cavity, this pathologic chorionic vesicle is of special interest 

 also in the absence of coagulum or so-called magma. The chorionic vesicle and 

 the space taken for the amniotic cavity were filled with perfectly clear fluid. Al- 

 though this small conceptus is markedly macerated, it is only in the early stages 

 of disintegration. Nevertheless, much longer retention might have resulted in its 

 complete dissolution, even if not its complete absorption. Since this small vesicle 

 was aborted in its entirety with blood-clot, it is highly probable that most of these 

 degenerative changes occurred after it was loosened from the implantation site, 

 probably by rupture of the decidua capsularis in consequence of hemorrhage. 



In other older conceptuses in earlier stages of disintegration, as No. 2047, 

 the amnion is preserved and distended, as shown in figure 173 (plate 16, Chap. 

 XI). Both chorion and amnion are macerated and distended with clear fluid, 

 and it seems strange indeed that the embryo and the yolk-sac may disappear 

 completely without even a final clouding of the amniotic fluid. There may have 

 been temporary clouding, but every now and then a specimen is received in which 

 both the vesicles are distended with absolutely clear fluid, a fact which also implies 

 that autolysis of the embryo occurred without digestion of the enveloping amnion. 



Since only a pseudo-decidua forms, and then but rarely and very early, in 

 cases of tubal pregnancy, the sequence of events leading to dissolution of the 

 conceptus must be rather different. There can be no accumulation of blood in a 

 capsularis. Hence the conceptus usually becomes isolated in blood or blood-clot 

 within the tube, and undergoes degeneration as the hemorrhage continues and the 

 tube becomes distended. If detachment of the conceptus occurs very early, it 

 is conceivable that it may undergo complete disintegration also within the tube, 

 that the latter may heal and the symptoms subside completely. While the occur- 



