VESSELS OF SYNOVIAL MEMBRANES. 



203 



tlieir offsets form a close network of anastomosing channels which, as 

 Eeyher has proved,* are occupied by cell-protoplasm (fig. 135). Such 

 networks are met with more ^frequently in some animals (ox) than in 

 man. 



The cells of the vaginal synovial membrane are often slightly elongated 

 in the direction of the axis of the tendon. 



The articular synovial membranes pass, as before said, a certain 



Fi-. 13(3. 



Fig. 136. — Traxsitio^j op 

 Cartilage Cells into 

 Connective Tissue Cor- 

 puscles OP Synovial 

 Membrane. About 



340 Diameters. From 

 Head of Metatarsal 

 Bone, Human. 



a, oi'dinary cartilage 

 cells ; J), h, with branclied 

 processes. 



distance over the car- 

 tilages of the joints. 

 They do not, how- 

 ever, end abruptly, but shade off gradually into the surface layer^ of 

 cartilage, the fibrous tissue disappearing and the cells gradually losing 

 their processes and becoming transformed into cartilage cells (fig. 136), 

 so that it is difficult to say for certain where the one begins and the 

 other ends. This portion of the synovial membrane, which overlies the 

 edge of the cartilage, is known as the "marginal zone ;" it is most 

 marked around the convex heads of the bones, and is especially well 

 seen near the lower margin of the patella (Hilter). 



The Haversian folds and fringes, at least the larger ones, agree in 

 general structure with the rest of the tissue of the synovial membrane, 

 (except that, as before remarked, some of them contain fat); their surface 

 layer contains for the most part irregularly stellate cells, except over 

 the fat, where we have occasionally observed a true epithelioid arrange- 

 ment like that of a serous membrane. The smaller non-vascular 

 secondary fringes of Rainey are minute finger-shaped processes pro- 

 jecting from the margins of the larger ones, and consist for the most 

 part of small rounded cells with granular protoplasm and but little 

 intercellular substance ; some of them may contain a few connective 

 tissue fibrils or even one or two cartilage-cells (Kolliker). 



Vessels. — The blood-vessels in and immediately underneath the 

 membrane are sufficiently manifest in most parts of the joints. They 

 advance but a little way upon the cartilages, forming a vascular zone 

 around the margin of each, named " circulus articuli vasculosus " (W. 

 Hunter), in which they end by loops of vessels dilated at the bent 

 part greatly beyond the diameter " of ordinary capillaries (Toynbee). 

 In the foetus, these vessels advance further upon the surface of the 

 cartilage. 



The vessels of the vaginal synovial membranes are less numerous than 

 those of the synovial membranes of the joints. 



Journal of Anatomy and Pliysiology, May, 1874. 



