558 STRUCTURE OF THE SYNOVIAL MEMBRANES, BY E. ALBERT. 



In the synovial membrane, however, there is a zone, the zone 

 of attachment, which in one direction is continuous with the 

 cartilage, but in the opposite forms a serous membrane. The 

 question now arises, whether on the other side of that zone, or, 

 to speak more accurately, between the two zones of attach- 

 ment (since the synovial membrane is extended between two 

 lines of bone), the membrane preserves the character of a serous 

 membrane in the strict sense of the term. It requires to be 

 determined whether the difference is sufficiently well marked 

 to cause a distinction to be made between the synovial and 

 serous membranes. 



The differences are as follows : First, it may be seen in 

 the most successful specimens that the trellis-work of the 

 cementing material does not everywhere present such fine and 

 uniformly broad lines as in the serous membranes ; and that the 

 size and form of the cells, and the character of their nuclei, vary 

 to a much more remarkable extent than in them. Secondly, 

 villi are as a rule met with in most joints, as well as in many 

 sheaths of tendons. I have even observed them in the joints 

 of new-born children. Hiiter has also stated, as a farther 

 point of distinction, that the vessels of the synovial membrane 

 are naked. This feature would certainly be of great import- 

 ance were Hiiter 's statement quite correct; but it may be 

 shown that where the layer of investing cells covers the layer 

 of serous canals the cells are also continued over the vessels. 

 In the same way it appears to me that the cells in question 

 are to be distinguished from the endothelia essentially by the 

 circumstance that in the Frog, where the endothelia are so 

 highly developed, such cells are not present on the inner side 

 of the joint, but that there are others which in all these 

 characters agree with the epithelioid cells of Mammals. 



Bohm, again, has declared that in the true serous mem- 

 branes the epithelial layer is never extended over fat, where 

 this occurs, as is the case with the synovial membranes ; and 

 he has also further stated that the superficial cells cannot be 

 pencilled away. But as regards the first point, it is to be borne 

 in mind that in true serous membranes the endothelial markings 

 do cover the fat cells. I thus maintain, in opposition to Hiiter, 

 that the synovial membrane of the articulations possesses two 



