354 



MANUAL OF HISTOLOGY. 



Fig. 343. Network of blood-vessels from 

 peptic gland of the human stomach. 



liver (fig. 345), is extremely dense surrounding the cells (comp. fig. 328), 

 partly with roundish and partly with more or less radiating loops. 



With the exception of the latter anomalous organ, we never find the 



capillary networks situated actually 

 among the groups of cells them- 

 selves, but external to the mem- 

 brana propria or envelope of connec- 

 tive-tissue. 



In those cases in which the vessels 

 penetrate into the interior through 

 the enveloping structures, as in 

 Peyer's glands and lymphatic knots, 

 the part is improperly termed a 

 secreting organ, and belongs rather 

 to the lymphatic formations. 



The energetic transformation of 

 material which takes place in glands, 

 appears as a rule to necessitate the 

 presence in them of lymphatics, an 

 acquaintance with the nature of 

 which has recently been gained with 

 greater accuracy than was previously 

 possible. The testicle and thyroid 

 gland (fig. 344, d, and 346, d-f) may 

 be mentioned as examples. 



With the consideration of the 

 nervous supply of glands, we come to one of the most obscure points in 

 histology. The nerves here met with consist partly of Remaps fibres, 

 and partly of medullary elements. Their distribution is in the first 

 place to the blood-vessels of the organ, then to the excretory ducts and 

 secreting elements of the latter. As a rule, but few and scattered nerves 



can be recognised in glands, 

 but that several of the latter, 

 as, for instance, the lach- 

 rymal and salivary, are richly 

 supplied with them has 

 v already been mentioned in 

 a previous section ( 189). 



Unstriped muscle may also 

 be an important element in 

 the structure of glands. 

 Thus, without taking into 

 consideration the muscular 

 structures around the effe- 

 rent ducts, we may see in 

 the first place narrow 

 bundles, ascending between the individual glands, as, for instance, in the 

 mucosa of the stomach, or the same may be observed in the connective- 

 tissue enveloping the several sub-divisions of the organ, as in the prostate 

 and Cowper's glands (Koelliker). The wall of the organ again may be 

 muscular, as best seen in the large sweat glands of the axilla. 



The excretory passages of glandular organs must now be specially de- 

 scribed. We have already seen that these are not indispensable to the 



rig. 344. From the testicle of the calf. At (a) the seminal 

 tubules are seen somewhat from the side; at (6) trans- 

 versely; c, blood-vessels; rf, lymphatic passages. 



