THE CONNECTIVE TISSUES. 



FIG. 43. 



Peripheral part of a tendon in section : a, external 

 fibrous investment sending partitions between the 

 secondary groups (6) of the tendon-fibres ; the small 

 stellate figures represent the stained contents of the 

 interfascicular clefts. 



arrangement of the white fibrous element, while its extensibility is 

 determined by the proportion of elastic tissue present. When the 

 former occurs in well-defined 

 bundles, felted together into 

 interlacing lamellae, dense and 

 resistant structures result, as 

 fasciae, the cornea, etc. ; in 

 such structures the cement- 

 substance within the interfas- 

 cicular clefts is usually hol- 

 lowed out to form the spaces 

 occupied by the connective- 

 tissue cells and their pro- 

 cesses. 



Tendon represents a dense 

 connective tissue, composed 

 almost entirely of white 

 fibrous tissue arranged in parallel bundles of varying thickness. 

 The primary bundles, made up of the ultimate fibrillae, are held 

 together to form larger secondary ones, which latter are enveloped 

 in a delicate sheath covered by endothelial plates ; the secondary 

 bundles are bound together and grouped by connective-tissue septa, 

 which are extensions of the thick external sheath wrapping the 

 entire tendon. The larger septa support the blood and lymphatic 

 vessels. 



The flattened connective-tissue corpuscles, or tendon-cells, occur 

 in rows within the clefts, between the primary bundles, upon and 

 between which the thin, plate- 

 like bodies and wings of the FIG. 44- 

 tendon-cells expand. Seen 

 from the surface, these cells 

 appear as quadrate bodies, 

 whose oval nuclei are frequently 

 so disposed that those of two 

 neighboring cells are in close 

 proximity, lying near the ad- 

 jacent ends of the cells, from 

 which arrangement it follows 

 that each pair of nuclei is sep- 

 arated by the greater part of the length of two cells. Viewed in 

 profile, the tendon-cells show as narrow, irregularly rectangular 

 bodies; while when examined in transverse section the same cells 

 appear as stellate bodies, whose extended arms, passing often in 

 several planes, represent the sections of the wing-plates. Each cell 



Primary bundles of white fibrous (tendon) tissue, 

 on and between which the flattened tendon-ceils lie : 

 at J these are seen from the surface ; at o and /, 

 oblique and profile views. 



