848 



THE INTESTINE. 



open glands, there is not sufficient evidence to show whether their contents pass 

 into the intestinal tube or into the lacteals, from which they are as completely sepa- 

 rated by intervening texture. The facts which have been ascertained as to their 

 minute structure, and the nature of their contents, seem to bring them rather under 

 the description of vascular glands. It may farther be stated as a point of analogy 

 between them and those structures, that the glands of Peyer belong chiefly to youth. 

 After middle life they become more or less flaccid and empty, and have generally 

 completely disappeared in advanced age. 



Fig. 593. 



Fig. 593. VERTICAL SECTION OP A PORTION OF A PATCH OF PETER'S GLANDS, WITH 

 THE LACTEAL VESSELS INJECTED (from Frey). ^ 



The specimen from which the drawing was made was obtained from the body of a man of 

 twenty years of age who died suddenly from an injury, and is from the lower part of the 

 ileum ; the epithelium, not represented in the original, is introduced diagram matically in 

 one part : a, villi, with their lacteals left white ; 6, some of the tubular glands ; c, the 

 muscular layer of the mucous membrane ; d, the cupola or projecting part of Peyer's 

 vesicles ; e, their central cavities or substance ; /, the reticulated lacteal vessels occupying 

 the "lymphoid" tissue between the vesicles, joined above by the lacteals from the villi 

 and mucous surface, and passing below into g, the reticulated lacteals under the vesicles 

 of Peyer, which pass into g', the larger lacteals of the submucous layer i. 



The observations of Frey and His have further shown that in the intervals between 

 the glands of Peyer and those of Lieberkiihn, and also in the substance of the villi, 

 the interstices of the retiform tissue (see Histology, p. Ixxix), are everywhere occupied 

 by granular cells of the size and appearance of lymph-cells, and very similar to those 

 contained in the capsules of Peyer's glands. 



In all, from twenty to thirty of these oblong patches may in general be 

 found ; but in young persons dying in health, as many as forty-five have 

 been observed. They are larger and placed at shorter distances from each 

 other, in the lower part of the ileum ; but in the upper portion of that 

 intestine and in the lower end of the jejunum, the patches occur less and 

 less frequently, become smaller, and are of a nearly circular form ; they 

 may, however, be discovered occasionally in the lower portion of the duo- 

 denum. 



