Chap. 7 



TISSUES 



111 









Fig. 7.4. Simple columnar cells in a gland in the human uterus. Droplets of the 

 secretion have collected at the ends of the cells and are about to pass through the 

 membranes; other droplets are free of the cells in the cavity of the uterus. All the 

 epithelial cells have polarity, most striking in the ciliated and glandular ones. 

 Preparation by Dr. G. N. Papanicolaou. xl200. (Courtesy, Nonidez and Windle: 

 Textbook of Histology, ed. 2. New York, McGraw-Hill Book Co., Inc., 1953.) 



ones are dead and horny (Fig. 8.2). They are constantly being worn away at 

 the surface and replaced in the deeper layers. Stratified epithelium is extremely 

 thick in the footpads of large carnivores — tigers, lions. 



Connective Tissue, Including Blood and Supporting Tissues 



Connective tissue contains a large amount of nonliving intercellular sub- 

 stance, fibers in connective tissues, tough resilient chondrin in cartilage, hard 

 rigid substance in bone, and the fluid plasma in blood (Fig. 7.5). 



Connective tissue connects and binds together the tissues and organs of the 

 body. It seems ever present, penetrating into glands and muscles along with 

 the blood vessels, and binding nerve and muscle fibers into compact bundles. 

 If all other tissues were destroyed, the body with its organs would keep its 

 shape because of connective tissue. During dissection its whitish sticky strands 

 have to be pushed aside and torn. In beefsteak and roast beef such strands 

 display their tough and threadlike quality. Surface wounds are closed mainly 

 by connective tissue and scars of all kinds are chiefly composed of it. 



Loose areolar or open tissue is the papery fastening which must be torn 

 as one skins any animal, especially birds and mammals. This most generalized 

 connective tissue supports and surrounds other tissues and is a living pack- 

 ing material in the body. 



The substances which other tissues receive from the blood and lymph — 



