MUSCULAR TISSUES 



colored intensely by acid stains, such as 

 eosin, (c) the giant cells, which are very 

 large, but contain only one nucleus, (d) 

 the erythroblasts, which are nucleated red 

 blood-cells. In addition to these, the 

 red marrow contains mast-cells, fat- 

 cells and osteoclasts, or multinuclear 

 giant-cells. 



(2) Yellow bone marrow is formed 

 from red marrow by the infiltration of 

 fat-cells which convert it into adipose 

 tissue. When examined in section 

 yellow marrow resembles ordinary fat- 

 tissue, consisting chiefly of large com- 

 pressed spherical fat-cells which are 

 supported by a reticulum of connective 

 tissue. Yellow marrow is found in all 

 the adult long bones, except at their 

 extremities. 



The Muscular Tissues. 



The chief characteristic of muscular 

 tissue which distinguishes it from all 

 other tissues is its marked contractility. 

 This variety of tissue may be divided 

 into three large groups: (i) Striated 

 muscle, (2) cardiac muscle and (3) smooth 

 muscle. 



(i) Striated or voluntary muscle 

 makes up the greater part of all the 

 skeletal muscles by means of which all 

 voluntary movements are made. In 

 addition to this, it constitutes the walls 



FIG. 16. Two fibers of 

 striated muscle, 



In which the contractile 

 substance, m, has been rup- 

 tured and separated from the 

 sarcolemma, a and s; p, space 

 under sarcolemma. (From 

 Yeo after Ranvier.) 



of the abdomen, and a 



