34 



CELL DIFFERENTIATION AND THE ELEMENTARY TISSUES 



Adenoid or retiform. 

 Adipose. 

 Neuroglia. 

 Cartilage. 



1. Hyaline. 



2. White fibrous. 



3. Elastic. 

 Bone and dentine. 



The White Fibrous Tissue. It is found typically in tendon; also in 

 ligaments, in the periosteum and perichondrium, the dura mater, the peri- 

 cardium, the sclerotic coat of the eye, the fibrous sheath of the testicle, in the 

 fasciae and aponeuroses of muscles, and in the sheaths of lymphatic glands. 



Structure. To the naked eye, tendons and many of the fibrous mem- 

 branes, when in a fresh state, present an appearance as of watered silk. 



FIG. 38. 



FIG. 39. 



FIG. 38. Mature White Fibrous Tissue of Tendon, Consisting Mainly of Fibers with a 

 Few Scattered Fusiform Cells. (Strieker.) 



FIG. 39. Caudal Tendon of Young Rat, Showing the Arrangement, Form, and 

 Structure of the Tendon Cells. X 300. (Klein.) 



This is due to the arrangement of the fibers in wavy parallel bundles. Under 

 the microscope the tissue appears to consist of long, often parallel, bundles 

 of fibers of different sizes. The cells in tendons, figure 39, are arranged 

 in long chains in the ground substance separating the bundles of fibers, and 

 are more or less regularly quadrilateral with large round nuclei containing 

 nucleoli, generally placed so as to be contiguous in two cells. Each of 

 these cells consists of a thick body from which processes pass in various 

 directions into, and partially fill up the spaces between, the bundles of 

 fibers. The rows of cells are separated from one another by lines of cement 

 substance. 



Yellow Elastic Tissue. Yellow elastic tissue is found chiefly in the 

 ligamentum nuchae of the ox, horse, and other animals; the ligamenta sub- 



