100 



SPECIAL HISTOLOGY. 



(fig. 206) ; in the former, we observe that the glands do not 

 occupy the whole surface, but only the interspaces between 



Fig. 212. 



the villi; here, however, they 

 exist in such numbers, as to 

 leave no intervals of any width, 

 the mucous surface between the 

 villi appearing pierced like a 

 sieve. Even on Peyer's patches 

 and over the solitary follicles, these 

 glands are to be met with; but 

 in man, they leave those portions 

 of the mucous membrane which lie 

 immediately over the centre of the 

 follicles free, and therefore are 

 arranged like rings around the 

 follicles. The length of the Lieberkuhnian glands equals the 

 thickness of the mucous membrane and varies from } — }'"; 

 their breadth is 0'028— 0-036'"; that of their aperture, 0'02— 

 003"'. They are composed of a delicate homogeneous mem- 

 brana propria and of a cylindrical epithelium, which, even 

 during chylification, never, like that of the intestine, contains 

 fat ; their cavity is filled, during life, by a clear, fluid secretion, 

 the so-called intestinal juice, which, however, becomes rapidly 

 changed after death, or on the addition of water, so that the 

 glands appear to be filled with cells, or with a granular mass. 



The vessels of Brunner's glands have the same arrangement 

 as those of the salivary, whilst around Lieberkuhn's caeca 

 they follow exactly the type of those of the stomach. A fine 

 network of capillaries of 0003'" passes up round the caeca and, 

 upon the surface of the mucous membrane, enters an elegant 

 polygonal reticulation of somewhat wider (0'01'") vessels, which 

 communicates on one side with the vessels of the villi, on the 

 other is directly continuous with veins, which, after communi- 

 cating with those of the villi, run directly out of the mucous 

 membrane. Hence, in this case also, the veins are connected 

 only with the superficial network round the glandular apertures 

 and w r ith that in the villi, but not with that which surrounds 

 the glands, so that, as in the stomach, the vessels which 



Fig. 212. Lieberkuhnian glands of the Pig, x 60 : a, membrana propria and 

 epithelium ; b, cavity. 



