CHAPTER II 



HISTOLOGY 



Histologj' is the stiich^ of the muuite structure of the tissues 

 of the body. Since it is carried out by means of the microscope 

 it has been described as IVIicroscopic Anatomj'. 



The tissues of which the different organs are composed may 

 be divided into four main groups as follows : 



(1) Epithelial tissues. 



(2) Connective tissues. 



(3) Muscular tissues 



(4) Nervous tissues. 



(1) Epithelial Tissues. 



An epitlielium may be defined as a cellular membrane bound- 

 ing a free surface. There is a certain amount of cementing 

 substance present between the cells, but this is reduced to mini- 

 mal proportions. There are two main kinds of epithelia, simple 

 and compound. 



In simple epithelia the cells form one layer onl^^ They may 

 be cubical in shape like those lining the tubules of certain glands 

 such as the pancreas, or columnar like some of the cells lining 



^ ' ■■''^^fiB 



Fig. 3. Columnar epithelium from intestinal 

 villus (from Gray). 



the inside of the stomach or intestine. They may be provided 

 with cilia or fine filaments, as A\ith the cells of the uterus, in which 

 case we speak of a ciliated epithelium. Moreover the lining 

 membrane may consist of a layer of thin cells arranged in the 



