RELATION OF VESICULAR MOLE TO CHORION CARCINOMA 147 
the more compact. In only one of my cases was there an amniotic sac (see Fig. 6, 
Plate IX), and there the mole was unusually compact, only small vesicles being present. 
There was, however, no trace of a foetus in any of the specimens. 
The mole may be any size from two or three up to nine or ten inches in 
length, the size as previously indicated not having any definite relation to the length 
ot the pregnancy. 
The fluid contained in the vesicles is thin, clear, and watery, having a slightly 
reddish tinge, ot low specific gravity, neutral in reaction, containing mucin and derived 
albumins, and debris ot highly refracting granules which do not stain with osmic 
acid. 
The mucin, which is a glycoproteid, is insoluble in water, and does not dialyze, 
it has, however, a marked capacity for taking up water, and this is easily demonstrated, 
for when a mole is placed in that medium, the cysts swell up and may become quite 
twice their original size. It has been said by some observers that vesicular moles do 
not contain mucin, but in each case I have examined, the chemical tests for mucin 
have given a positive result. 
The fluid found in these cysts is formed by the breaking down of the myxo- 
matous tissue of the central core ot the vesicle, and to appreciate fully the minute 
chances which occur in this condition, it is necessary to have a clear idea of the struc- 
ture of the core of the normal villus. 
Here the stroma consists of connective tissue cells, which vary greatly in size 
and shape. Some are large with polygonal outline, having a long wavy process from 
each angle. The body ot the cell is rich in protoplasm, and contains a centrally 
placed nucleus, which stains well with haematoxylin. The processes intertwine with 
those ot neighbouring cells, so forming a complete network. Other cells are smaller, 
and tend more to the round or ovoid shape ; they possess a well-stained nucleus, 
with one or more nucleoli, and are seen scattered irregularly throughout the stroma. 
In a lull term villus, the stroma often presents a finely fibrillated appearance, with 
comparatively few nuclei. This is most marked in the neighbourhood of the 
capillaries, where the fibnllae assume a concentric arrangement enclosing the blood 
vessel, the wall of which is only represented by a single layer of flattened endothelial 
cells. The capillaries may be so large as to occupy almost all the stroma, or there 
may be a number of small ones in the same villus. These contain toetal blood 
shewing nucleated red blood corpuscles during the early months of pregnancy, 
poikilocytes, microcytes, and many varieties of leucocytes. 
In vesicular mole, the stroma presents a strikingly different aspect. There is 
a marked absence of nuclei, the main mass of the stroma being made up of a few 
myxomatous cells with very long branching processes. The cells are much elongated, 
their nuclei are rod shaped, oval, or round, according to the pressure or stretching 
to which they are subjected. Between the cells is seen the finely granular matrix 
