SECT. 20.] 



EPIDERMIC TISSUE. 



35 









Epithelial cells from vessels ; 

 the longer ones from arteries ; 

 the shorter from veins. 



in three ways, viz., into plates, flat fibres, and rounded polyhedral 

 cells. 



2. As Epithelium. — With soft (never cornified) nucleated cells, 

 which have a roundish, polygonal, fusiform, cylindrical or conical 

 figure, and are sometimes ciliated, sometimes not ; and which are 

 arranged in one of several layers, whence arise the following 

 varieties : — 



a. Epithelium of one layer. 



i. With roundish, poly tonal cells (simple pavement-epithelium, 

 or simple tesselated epithelium). This is Rg-6. 



found lining the true serous membranes, most 

 of the synovial membranes, the ventricles 

 of the brain (ependyma), the membrane of 

 Demours, the anterior surface of the iris, 

 also on the inner surface of the choroid, as 

 far as the ora serrata (pigment layer), the 

 inside of the anterior half of the capsule of 

 the lens, the periosteum of the internal ear, 

 the inner surface of the tubuli membranacei 

 and sacculi of the latter, the inner surface of 

 the endocardium and veins, of many glandular vesicles and canals 

 (racemose glands, kidneys, sudoriferous glands, cerumincus glands, 

 lungs), and the interlobular ducts of the liver (fig. u). 



2. With fusiform cells, arranged collaterally in the same surface 

 (fusiform epithelium). Epithelium of arteries, and of many 

 veins (fig. 6). 



3. With cylindrical cells (cylindrical epithelium, columnar epi- 

 thelium). This form is found in the alimentary canal, from the 

 cardia to the anus, in the Lieberkiihnian follicles, the excretory 

 ducts of the gastric glands, in all other glands opening into the 

 intestine, as well as in the mammary and lachrymal glands ; fur- 

 ther, in the male urethra, the ras deferens, the seminal vesicles, the 

 excretory ducts of the prostate, in Cowper's, Bartholine's, and the 

 uterine glands (fig. 7). 



4. With cylindrical or coni- 

 cal ciliated cells (ciliated, sim- 

 ple cylindrical epithelium). 



Epithelium of the finest 

 bronchia, of the accessory ca- 

 vities of the nose, of the inner 

 side of the membrana tympani, 



•J r hiutliulium of the intestinal villi of the 



of the Eustachian tube and magnified 300 times. 



D 2 



Fig. 7. 



rabbit' 



