EXPERIMENTALLY PRODUCED EXTRAUTERINE PREGNANCY. 67 



general view concerning the time of fertilization of the guinea- 

 pig ovum already taken place at the time of the operation. We 

 excised the nodule fifteen days eight hours after the incisions had 

 been made. 



Our description of the embryo clearly shows that under the 

 existing abnormal conditions the development of the ovum was 

 greatly retarded. The embryo is still alive and even growing, as 

 the mitoses, which were found at various places, indicate, but the 

 embryo is found to be at a very much earlier stage of development 

 than one would expect eighteen days after copulation. The 

 embryonal placenta also is only very incompletely developed. 

 While the normal placenta of the guinea pig shows a complicated 

 structure at this period of development, in our case the embryonal 

 placenta consist solely of layers of small cuboidal cells, which 

 usually line cavities, and produce papillary excrescences pro- 

 jecting into the cavities. On the outer side of these cavities 

 there are giant cells . The gia nt cells penetrate also independently 

 into the surrounding connective tissue and substitute walls of 

 blood vessels, and thus contribute to the hemorrhages which we 

 find so frequently. Cuboidal cells as well as giant cells are 

 growing actively by mitosis — the latter however to a lesser 

 degree. The surrounding host tissue remains passive. The 

 embryonal tissue is surrounded by fibrillar connective tissue 

 containing the ordinary connective tissue cells. There is no- 

 where an attempt at the formation of a decidua on the part of the host 

 tissue. 



These observations are in entire accord with our former ex- 

 perimental findings from which we concluded that in the guinea 

 pig solely the connective tissue of the uterine mucosa is able to 

 produce decidua in response to artificial stimuli, as cuts and 

 foreign bodies while the fallopian tube, peritoneal and other con- 

 nective tissue are unable to do so.^ 



These additional observations again prove the similarity in the 

 mode of action of the artificial stimuli leading to the formation of a 

 decidua on the one hand and of the ovum on the other hand. In a 

 similar manner as the artificial stimuli were not able to call forth a 



iLeo Loeb, Zentralblalt fiir Physiol, Bd. XXIII., No. 3; Journal Am. Med. 

 Association, Vol. LIIL, p. 1471. ipop- 



