7 6 



HISTOLOGY 



P .b 



delicate tendons found in the tail of a rat or mouse (Fig. 63), it is seen that 

 the cytoplasm of tendon cells forms a plate-like layer which is folded 

 about the fiber bundles, tending to encircle them. Moreover the cells 

 are provided with lamellar or wing-like projec- 

 tions, which extend out between adjacent fiber 

 bundles. Apparently there are protoplasmic 

 connections, end to end, between the cells, which 

 thus form longitudinal rows or chains; and in 

 cross sections of the tendon some of the wing-like 

 projections anastomose as seen in Fig. 64. Thus, 

 as in connective tissue, the original syncytial ar- 

 rangement of the mesenchyma is partially, pre- 

 served. 



The primary tendon bundles, which consist 

 chiefly of white fibers and tendon cells, contain 

 also a small amount of elastic tissue in the form of 

 fine, wide-meshed networks. The elastic fibers 

 are said to occur especially near the cells and their 

 processes. The primary bundles are generally 

 grouped in secondary bundles or fasciculi, which 

 are bounded by partitions or septa of looser con- 

 nective tissue (Fig. 65). Within the septa there are nerves and blood 

 vessels, in relatively small number. Lymphatic vessels are said to be 



FIG. 64. FROM THE CALCA- 

 NEAN TENDON (TENDO 

 ACHILLIS) OF A RABBIT. 

 (After Prenant.) 



p. b., Primary bundle bounded 

 by a cytoplasmic sheath. 

 sh., which extends from a 

 tendon cell, t.c. p., process 

 extending into a primary 

 bundle. The entire figure 

 is a portion of a secondary 

 bundle. 



.! 



: i 



Septum. Blood vessel. Fasciculus. Fibrous sheath. 



FIG. 65. FROM A CROSS SECTION OF A TENDON FROM AN ADULT MAN. X 40. 



confined to the sheath of connective tissue which surrounds the entire 

 tendon, with which the septa are continuous (Fig. 65). 



The fibrous sheath or vagina fibrosa, which surrounds the tendon, 



