CONNECTIVE TISSUES II 



dermis, especially of certain races, as the negro. It is also 

 found in the choroid coat of the eye. 



(d) Glandular epithelium may be columnar, spherical or 

 polyhedral in shape. It is found lining the terminal recesses 

 of secreting glands. The protoplasm of the cell usually con- 

 tains the material which the gland secretes. 



(e) N euro-epithelium is the name given to that covering 

 those parts toward which the nerves of special sense are di- 

 rected, and is epithelium of the highest specialization. It 

 occurs in the retina, the membranous labyrinth and in the ol- 

 factory and taste cells. 



The Connective Tissues. 



All these tissues are developed from the same embryonal 

 elements, but present varieties differing widely in appearance 

 and properties. They are characterized by the preponder- 

 ance of the inter-cellular over the cellular elements. The 

 physical characteristics of these tissues are very important 

 and depend mostly upon the intercellular elements. Their 

 purpose in the animal economy is to furnish a supporting 

 and connecting framework for the body. In the embryonal 

 state the intercellular substance is semi-fluid and gelatinous. 

 Later, in adult connective tissue it becomes more definitely 

 formed, although it is still soft. In adult areolar tissue the 

 intercellular substance becomes tough and yielding. When 

 this intercellular substance becomes impregnated with cal- 

 careous salts we hav6 bone. However, during all these 

 changes in the intercellular substance little or no change has 

 taken place in the cellular structure. The bone-corpuscle, the 

 cartilage-cell, the tendon-cell and the connective tissue-cell 

 are all essentially identical. 



The divisions of connective tissue are: (i) Mucous Tis- 

 sue, (2) Reticular Tissue, (3) Fibrous Tissue, (4) Adipose 

 Tissue, (5) Cartilage, (6) Bone. 



