The Adult Tissues of the Human Body 



27 



of longitudinal fibers within the tendon are also enclosed in sheaths of con- 

 nective tissue continuous with that of the larger sheath. 



Wherever the connective tissue fibers are found, the cells which nourish 



Fig. 16. Elastic cartilage (gristle) from human ear. Magnified about 290 diam- 

 eters. (Szymonowicz, Histologic.) Showing cartilage-cells, and elastic fibers. 



Osteoblast becoming a bone' cell. Bone cell.- Osteoblast. 



4 ■* • 



Uncalcified 

 — matrix. 



■Calcified 

 """ matrix. 



*«. 



% 



jf»; 



Fig. 17. Part of a cross-section of a bone from a four-month human embryo. Mag- 

 nified 675 diameters. (Lewis and Stohr, Histology.) 



them are found also. In the dense tissues the cytoplasm and nucleus may 

 be flattened between fibers or in thin plates wrapped around them. 



3. Bone and cartilage are produced by mesenchymal cells. Bone is 

 ■deposited by a specialized cell, the osteoblast, which as it encloses itself 



