THE SMALL INTESTINE. 



165 



pylorus, but are better developed in the second part, where they are low and 

 broad and measure .2 .5 mm. in height and .31 mm. in width. In the 

 jejunum the villi are conical and somewhat laterally compressed, while in 

 the ileum their shape is cylindrical, filiform or wedge-like and their height 

 from .5-1 mm. The villi are projections of the mucous coat alone (Fig. 

 204) and consist of a framework of the lymphoid stroma-tissue, covered by 

 columnar epithelium, supporting the absorbent vessel and the blood-vessels 



m 



Stroma of tunica propria- 



Lacteal 



urface epithelium 



T^Xv> '.'*'.* Si ! )$M1 ^'>--^,ViF5^}^ < 



fr3a.'f.&?.'* if Ji'rSK '2 K^ALiiVr^JJlm! 





;^>^ * -^ i^ ETtTPH --7> > "3- - j> 



Submucous coat ' ":~"T^.V.-l^'l r ^r 



Gland of Licberkuhn 



Muscularis mucosae 



Circular muscled. 



FIG. 204- Transverse section of small intestine (jejunum), showing the villi cut lengthwise. X 150. 



and intermingled with a few strands of unstriped muscle. The supporting 

 framework of the villus a complex of fibrous, reticular and elastic tissue is 

 condensed beneath the epithelium into a delicate membrane. The lacteal, 

 as the absorbent vessel or lymphatic occupying the villus is usually termed, 

 begins as a blind, often slightly club-shaped channel, which runs through 

 the centre of the villus, surrounded by the delicate muscle-bundles and the 

 blood-capillaries. While the slender cylindrical villi possess a single lacteal 

 (25-35 !" m diameter), those of broader form often contain two, three or even 

 more such vessels, which may communicate by cross-channels. Their walls 



