NON STRATIFIED EPITHELIA 



3!) 



2. SIMPLE COLIMXAI; KI-ITHELIUM 



(a) J'lain 



This type of epithelium consists cf columnar or cylindrical elements 

 (Fig. 30), in transverse section presenting polygonal, frequently hex- 

 agonal, outlines (Fig. 40). It 

 may be tall, medium or low 

 columnar epithelium, depend- 

 ing upon the height of the in- 

 dividual cell of the particular 

 membrane. The lower types 

 may be designated cuboidal 

 epithclia (Fig. 43). The phe- 

 nomenon of polarity is partic- 



ELIUM FROM THE 

 s OF THE RABBIT. 



FIG. 43. C 



RETE TES 



a, epithelium; b, connective tissue. Hema- 

 tein and eosin. X 550. 



ularly well exhibited by a tall 

 columnar cell, a condition inhering 



FlG. 44. TIP OF A VlLLUS OF THE 



SYNOVIAL MEMBRANE FROM THE 

 KNEE-JOINT OF AN OLD MAN. 

 The core contains capillaries em- 

 bedded in a compact, delicately fibrillar 

 stroma. A distinct basement mem- 

 brane appears in certain regions. The 

 epithelium is of the low columnar or 

 cuboidal type. 



in a structural and functional differ- 

 entiation between the attached, or 

 proximal, and the free, or distal, end 

 of the cell, dependent in a final an- 

 alysis in larger measure upon dis- 

 tance from source of the nutritive 

 and oxygenative stream in the blood. 

 The nucleus is generally located 

 nearer the proximal end; this end, 

 moreover, tapers to a point and is 

 occasionally bifid; and it contains 

 the presecretion (ergastoplasm, pro- 

 xy mogen, etc.) granules, rodlets and 

 fibrils in secreting epithelia (Fig. 

 35 ) . The distal border is frequently 

 striated (cutieular margin, striated 

 border, Fig. 38, b), an appearance 

 due to the presence of minute canals, 

 or more frequently, short pseudo- 

 podia, mediating absorption or the 

 elimination of secretion. Striated 

 borders are particularly prominent 

 in the columnar cells of the intes- 

 tine. In the secreting cells of tiro 



