HOFBAUER CELLS. 311 



and not infrequently lie in detritus. The better preserved the stroma the fewer 

 cells one finds, and in these observations on this rather large series of chorionic 

 vesicles, some of which were obtained fresh one living in hysterectomy speci- 

 mens, I have found only a few instances of what possibly could be regarded as 

 mitotic figures. Since almost all are agreed that these cells are of mesenchymal 

 or connective-tissue origin, it is easy to see that considerable difficulty must be 

 encountered in deciding just when to regard a mesenchyme cell, which is its pre- 

 cursor, as a Hofbauer cell. Since I have not made this aspect of the question a 

 particular subject of investigation, I have no evidence to offer on this point. 



Since some of these cells, during the early period of degeneration, after they 

 have become quite circular in outline and the nucleus has taken an eccentric 

 position, have a decidedly granular or even a lumped cytoplasm, the confusion 

 with plasma cells, or their earlier designation as granular wandering cells, need not 

 surprise us. Nevertheless, the term plasma cells is hardly applicable, as many of 

 them are not granular. Moreover, no one has shown that in fixed preparations 

 these cells take the stains specific for plasma cells. Indeed, although he stained 

 material with borax methylene-blue after Jadassohn, Happe (1906) did not find 

 any of the Hofbauer cells impregnated. It must be remembered, however, that 

 failure to stain may be dependent very largely upon the degree of degeneration 

 which the particular cells have undergone, for, as already stated, Hofbauer found 

 that in fresh material they reacted as plasma cells to vital stains. 



The opinion of Minot that Hofbauer cells are degenerating erythrocytes can 

 probably be accounted for by the fact that in the chorionic vesicle from which 

 Minot's series, showing a progressive degeneration of the latter into the former, 

 was obtained, it was impossible to distinguish between the two. This difficulty was 

 due partly to the poor state of preservation of the particular specimen. A larger 

 survey, especially of better preserved material, would have revealed the fact that 

 Hofbauer cells are found in villi, the blood-vessels of which contain no erythro- 

 blasts. Moreover, as will appear later, the distribution of Hofbauer cells in the villi 

 is not such as one rightfully would expect if they have their source in the vessels. 

 However, since the final form of the typical Hofbauer cell is a mere shadow cell, 

 it necessarily may be impossible to determine the kind of cell from which this 

 shadow form arose, for, as is well known, the end-forms in the process of degenera- 

 tion of many different types of cells are indistinguishable. Consequently, a group 

 of swollen, highly vacuolated Hofbauer cells may also contain among them degen- 

 erated, nucleated red blood-cells, as Minot held. Indeed, degenerating erythroblasts 

 which are indistinguishable from some Hofbauer cells can be seen occasionally 

 not only in the vessels, but in the heart itself, and also within the cavity of 

 the chorionic vesicle; but such findings do not prove that the Hofbauer cells 

 of the villi arise from erythroblasts. That this is usually not the case follows 

 also from the fact that well-preserved, non-vacuolated Hofbauer cells occur in 

 villi which have not become vascularized or which, as stated above, no longer 

 contain vessels. It is true that it is often impossible to distinguish between de- 

 generate erythroblasts within the vessels and Hofbauer cells lying outside of, even 









