CONNECTIVE TISSUES II 



certain races, as the negro. It is also found in the choroid coat 

 of the eye. 



(d) Glandular epithelium may be columnar, spherical or poly- 

 hedral in shape. It is found lining the terminal recesses of 

 secreting glands. The protoplasm of the cell usually contains 

 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 directed,, and 

 is epithelium of the highest specialization. It occurs in the 

 retina, the membranous labyrinth and in the olfactory 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 preponderance 

 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 inter- 

 cellular 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 sub- 

 stance becomes impregnated with calcareous salts we have 

 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 all being essentially identical. 



The divisions of connective tissue are: (i) Mucous Tissue, 

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

 (5) Cartilage, (6) Bone. 



