CELLS AND T/SSUES 59 



Table 1. COMPARISON OF VERTEBRATE MUSCLE TISSUES 



connective tissue. The latter classification is based on the fact that blood 

 cells and connective tissue cells originate from similar cells; however, 

 the adult cells are quite different in structure and function. The red 

 cells of vertebrates contain the red pigment hemoglobin, which has the 

 property of combining easily and reversibly with oxygen. Oxygen, com- 

 bined as oxyhemoglobin, is transported to the cells of the body in the 

 red cells. Mammalian red cells are flattened, biconcave discs without a 

 nucleus; those of other vertebrates are more typical cells with an oval 

 shape and a nucleus. 



There are five different kinds of white blood cells-lymphocytes, 

 monocytes, neutrophils, eosinophils and basophils (Fig. 3.14). These 

 have no hemoglobin but move around and engulf bacteria. They can 

 slip through the walls of blood vessels and enter the tissues of the body 

 to engulf bacteria there. The fluid plasma transports a great variety of 

 substances from one part of the body to another. Some of the substances 

 transported are in solution, others are bound to one or another of the 

 plasma proteins. The plasma of vertebrates is a light yellow color; in 



.sSi?^.^, 



^ 



H 



Figure 3.14. Types of white blood cells. A, basophil; B, eosinophil; C, neutrophil; 

 E-H, a variety of lymphocytes; I and /, monocytes; D, a red blood cell drawn to the 

 same scale. (Villee: Biology.) 



