358 



MANUAL OF HISTOLOGY. 



Fig. 351. Brunner's glands from the human duodenum, o, 

 villi; 6, bodies of the glands situated in the submucous 

 tissue, which empty themselves through their ducts between 

 the bases of the villi. 



The efferent, duct is at first narrow, later on expanded somewhat, and 

 loses its walls on penetrating the strata of the epithelium. The cells 



lining these glands are 

 usually roundish and flat- 

 tened, and possess a more 

 or less fatty contents. 



The complex tubular 

 glands present either a 

 homogeneous membrane, 

 as in the kidney, or this 

 is replaced by connective- 

 tissue, as in the testicle. 

 The seminal tubules of the 

 latter have a diameter of 

 about (HI 28 mm., and the 

 uriniferous tubes of the 

 former range from 0'2 and 

 1-2 to 0-0377 mm. and 

 upwards. These cells are 

 polyhedral, calling to mind 

 the appearance of flattened 

 epithelium. 



The physiological pur- 

 poses served by the several 

 kinds of tubular glands are 

 exceedingly various. 

 2. The racemose glands constitute a very large group of organs, varying 

 greatly both as to size, the character of the secretion yielded by each, 

 and their physiological significance. To these belong the many small glands 



of the mucous membranes of the 

 body. They occur with very dif- 

 ferent degrees of frequency ; often 

 as, for instance, in the mouth and 

 in the duodenum, they are very 

 densely crowded together (fig. 

 351). 



In different situations they 

 are known under special names, 

 as in the last case, where they 

 have obtained that of Brunner's 

 glands. The sebaceous glands of 

 the skin, likewise, with those 

 modified forms of them known 

 as the Meibomian of the eye- 

 lids, belong to this same cate- 

 gory. At the commencement 



Fig. 352. From the thyroid of the infant. of their development the first 



-c, glandular spaces. Qf ^^ ^^ themselves ag 



simple flask-shaped follicles, which are subsequently converted by saccu- 

 lation of their walls into smaller or larger racemose organs. 



Among the larger glands of this group may be reckoned the lachrymal, 

 the various salivary glands, the pancreas, the mammary, Cowper's and 

 Bartholini's glands in the organs of generation, as well as that aggregation 



d 



