INTESTINES. 



[ 440 ] 



INTESTINES. 



They vary in length from 1-60 to 1-84", and 

 consist of a delicate basement membrane, 

 lined with epithelium. 



Peyer's glands are rounded or elongated 

 flattened aggregations of glands, appearing 



Fig. 371. 



Magnified 10 diameters. 



Portion of a Peyer's gland, human : a, follicles sur- 

 rounded by the orifices of Lieberkuhn's glands ; b t villi ; 

 c, scattered Lieberkiihn'a glands. 



upon the inner side of the intestine as 

 slightly depressed spots. They are most 

 numerous in the ileum, but are sometimes 

 found in the lower part of the jejunum, or 

 even its upper part and the duodenum. 

 They are usually twenty, thirty, or more in 

 number. They vary in length from 1-25 

 to 1^". Each consists of an aggregation of 

 closed and rounded follicles, from 1-70 to 



Tig. 372. 



Solitary gland, covered with villi, from the jejunum. 



1-12" in diameter, partly seated in the mu- 

 cous membrane itself, partly in the sub- 

 mucous tissue. The follicles are surrounded 

 by a ring of Lieberkuhn's glands, which, 

 with villi, also occupy the intervening por- 

 tion of the mucous membrane. Each fol- 

 licle consists of a tolerably firm coat of 

 indistinctly fibrous areolar tissue, with scat- 

 tered nuclei, enclosing a grey soft sub- 

 stance consisting of innumerable nuclei and 

 cells, from 1-3000 to 1-1500" in diameter, 

 with a few granules of fat. The follicles 

 are surrounded by a vascular network, which 

 sends off branches to their interior. 



The solitary glands agree in structure 

 with the individual follicles of Peyer's 

 glands. Their free surface is usually con- 

 vex, and covered with villi (fig. 372). 



The glandular organs of the large intes- 

 tines are Lieberkiihn's glands and the soli- 

 tary follicles. 



The Lieberkuhn's glands agree in struc- 

 ture with those of the small intestines, 

 except that they are larger and broader in 

 proportion to the greater thickness of the 

 mucous membrane. The solitary follicles 

 also differ from those of the small intestine 



Fig. 373. 



Magnified 45 diameters. 



Solitary follicle from the colon of a child : a, tubular 

 glands; b, muscular coat of the mucous membrane ; c, 

 submucous tissue ; d, transverse muscular fibres ; e, pe- 

 ritoneum ; f, depression in mucous membrane over the 

 follicle g. 



in their larger size, and in the circumstance 

 that each of the minute elevations of the 

 mucous membrane produced by them 

 exhibits a rounded or elongated opening, 

 leading to a depression in the mucous 

 membrane over the follicle (fig;. 373). This, 

 however, has no communication with the 

 follicle. 



The investigation of the structure of the 

 intestines is a matter of some difficulty. 

 The epithelium must be examined in a 

 perfectly fresh state. The glands are 

 most readily seen in portions hardened by 

 absolute alcohol or chromic acid; whilst 

 some have recommended boiling with acetic 

 acid (80 per cent.), then drying and making 

 sections with a Valentin's knife. The 

 muscular elements are rendered most di- 

 stinct by maceration with dilute nitric acid 

 (20 per cent.). 



