HISTOLOGY. 



forms. Fluids circulate in them, conveying nutriment from the vessels 

 to epithelial and other cells and conducting waste products back to the 

 vessels. White blood corpuscles pass out between the endothelial cells 

 of the vessels to enter these spaces in which they may travel about or 

 multiply. Some corpuscles may originate in them, formed from adjacent 

 connective tissue cells. The intercellular or tissue spaces (lymph spaces) 

 differ from small vessels, either blood or lymphatic, in having no endothelial 

 walls; and the tissue fluid which they contain ordinarily differs from either 

 the blood plasma or the lymph. It undoubtedly resembles lymph with 

 which it has been considered identical. 



Summary of connective tissue. Connective tissue consists of inter- 

 cellular spaces and fluid, white fibers, elastic fibers, and cells. It sur- 

 rounds the various 

 organs, and through 

 it pass the nerves, 

 blood and lymphat- 

 ic vessels. Its spaces 

 areintermediate 

 paths between the 

 vessels and the cells 

 of the organs. Its 

 elastic fibers which 

 though varying in 

 size are not divisible 

 into smaller ele- 

 ments, form slender 

 networks or coarse 

 fenestrated mem- 

 branes, and are of 

 exoplasmic origin. 



Its white fibers are bundles of fibrils cemented together, and either densely 

 packed or loose and areolar. Its cells are those which produce the fibers 

 together with fat and pigment cells, and various forms lodged in the 

 intercellular spaces. These include lymphocytes, plasma cells, resting 

 wandering cells, mast cells, and eosinophiles. 



TENDON. 



Tendons consist essentially of very dense connective tissue with 

 parallel fibers. The dense tissue as seen in cross section, Fig. 50, is covered 

 by a sheath of ordinary connective tissue, prolongations of which extend 

 into the substance of the tendon. There they unite to form a network 





Septum. Blood vessel. 



I 

 Tendon bundle. 



J 



Fibrous sheath. 



FIG. 50. FROM A CROSS SECTION OF A TENDON PROM AN ADULT MAN. 

 X 40. 



