SECT. 169.] 



VESSELS OF THE SPLEEN. 



3*9 



spleen. The larger veins, so long as they accompany the arteries, 

 otter nothing for remark beyond their width. They all possess a 

 membrane, which is readily demonstrable, at least upon the side 

 nearest the arteries, and this gradually becomes attenuated, to- 

 gether with the' sheaths of the vessels. Openings of small veins, 

 the so-called stigmata Malpighii, are frequent in the sides of the 

 lesser splenic veins, but are found in smaller number on the main 

 branches. As they pass onward, after leaving the arteries, the 

 veins present a somewhat different arrangement. Firstly, a large 

 number of small veins pass off from them at all sides, and mostly 

 at right angles, so that their walls in some places appear perforated, 

 almost like a sieve. Secondly, their membranes completely coalesce 

 with the sheaths, so that, at last, the two only constitute a very de- 

 licate wall ; this wall, however, can be demonstrated with ease in the 

 finest vessels which are capable of isolation. I do not find enlarge- 

 ments in any part of these veins; and, it is only to be observed, 

 that they become attenuated more slowly than the arteries. As 

 for their connection with the capillaries, it takes place, in a part of 

 the vessels at least, just as in other organs, and is easily seen by 

 injection of a recent human spleen, especially in that of a child. 

 In rarer cases, this mode of connection may also be observed by the 

 microscope, for I have sometimes found small veins, in connexion 

 with the capillaries, in the interior of the Malpighian bodies ( Wurz. 

 Verh., iv., p. 58). I will not, however, affirm that all the arteries 

 and veins are connected in a regular manner through capillaries ; 

 for, in truth, all the more recent observations point to a connexion 

 in some way between the splenic pulp and the blood-vessels. We 

 must still hesitate, however, to receive any such view as demon- 



strated before it is thoroughly esta- 

 blished by facts. 



The epithelium of the splenic vessels, 

 especially of the vein, is readily de- 

 tached after death, and then appears 

 very large quantities, apparently 



Fig. 150. 



m 



free in the pulp. The cells are spindle- 

 shaped bodies, at first suggesting a 

 resemblance to those of plain muscular 

 fibre ; they have a nucleus, which is 

 frequently placed on one side. The 

 cells are frequently rolled up together, 

 and enclosed within a cell-like vesicle, 

 probably formed around them during death. 



Epithelial cells of the splenic vein 

 of man. Magnified 350 times. 



It was these cells 



I? B 



