THE CLOSED INTESTINAL GLANDS. 



605 



Fig. 104. 



fluid granular matter, containing mixed fatty and albuminous mole- 

 cules, nuclei, and cells, amongst which 

 loops of capillary vessels are said to pene- 

 trate from all sides. The mucous mem- 

 brane passes completely over these sacs, 

 and usually even a few villi are placed upon 

 them. In the large intestine, they are 

 situated at the bottom of a wide recess, 

 having a narrow orifice, which has been 

 erroneously regarded as an opening into 

 the sac. Secondly, clusters of these sacs, 

 the agminated glands, or Peyer's glands 

 (Peyer, 1677), are found in the small in- 

 testine only. These Peyer's patches, twenty 

 to thirty in number, are either rounded or 

 oval, being from half an inch to three or 

 more inches in length, and about half an 

 inch or more in width ; they are placed at 

 intervals, longitudinally along the free 

 border of the intestine (Fig. 91). Com- 

 mencing, of small size, in the lower part 

 of the duodenum, they gradually become 

 more frequent and larger in the jejunum 

 and upper part of the ileum, but are 

 largest and most numerous in the lower 

 part of the ileum. Their component sacs 

 (Figs. 98, 99), exactly resemble in struc- 

 ture the single sacs of the so-called solitary 

 glands. When distended, as occurs during the absorption of food, the 

 patches of Peyer's glands present a whitish speckled appearance, and, 

 if moderately magnified, each sac is seen to be surrounded by a little 

 zone of darkish points, which are the mouths of the crypts of Lieber- 

 kiihn, thrust outwards by the filling of the sac. The mucous mem- 

 brane over the sacs, is entire. Villi are seen in the intervals between 

 them, and sometimes, as is the case with the solitary glands, even upon 

 them. Opposite these patches, the submucous coat of the intestine is 

 more vascular than elsewhere, and especially abounds in lymphatics, 

 which, however, have not been traced into the sacs, but here form 

 plexuses of large and easily injected vessels. 



The sacs of both the solitary and the agminated glands are some- 

 times found open, as if by rupture through distension; but from their 

 normally closed condition, the fatty and albuminoid nature of their 

 contents, the abundance of lymphatics in their neighborhood, and from 

 the special distension of these, as well as of the sacs themselves, during 

 the process of intestinal absorption, it is with much reason inferred, 

 that both the solitary and agminated glands are concerned, in some 

 way, in this last-named function; the mode in which they act, and 

 the precise nature of their office, are, however, not yet understood. 



Fig. 104. Portion of the small intes- 

 tine, 1, 1, with its mesentery; 2, 2, 

 showing the superficial lacteal vessels 

 in the intestine and mesentery. The 

 mesenteric glands are also seen at 3 

 and elsewhere. 



