1282 



SPLANCHNOLOGY 



of each mass being grouped around a dilated sinusoidal capillary vessel. Each ce 

 contains a large round or oval nucleus, the protoplasm surrounding which is clea 

 and is not stained by chromic salts. 1 



THE SPLEEN (LIEN). 



L XO WlAxVVJ. ( 



The spleen is situated principally in the left hypochondriac region, but its supe- 

 rior extremity extends into the epigastric region; it lies between the fundus of the 

 stomach and the diaphragm. It is the largest of the ductless glands, and is of 

 an oblong, flattened form, soft, of very friable consistence, highly vascular, and 

 of a dark purplish color. 



Development. The spleen appears about the fifth week as a localized thickening 

 of the mesoderm in the dorsal mesogastrium above the tail of the pancreas. With 

 the change in position of the stomach the spleen is carried to the left, and comes 

 to lie behind the stomach and in contact with the left kidney. The part of the 

 dorsal mesogastrium which intervened between the spleen and the greater curva- 

 ture of the stomach forms the gastrosplenic ligament. 



Relations. The diaphragmatic surface (fades diaphragmatica; external or phrenic 

 surface) is convex, smooth, and is directed upward, backward, and to the left, 

 except at its upper end, where it is directed slightly medialward. It is in relation 

 with the under surface of the diaphragm, which separates it from the ninth, tenth, 

 and eleventh ribs of the left side, and the intervening lower border of the left lung 

 and pleura. 



Vein 

 leaving 



hilus 



FIG. 1188. The visceral surface of the spleen. 



The visceral surface (Fig. 1188) is divided by a ridge into an anterior or gastric 

 and a posterior or renal portion. 



The gastric surface (fades gastrica], which is directed forward, upward, and medial- 

 ward, is broad and concave, and is in contact with the posterior wall of the stomach; 



1 Consult the following article: " Uber die menschlicbe Steissdruse," von J. W. Thomson Walker, Archiv fur mikro- 

 skopische Anatomie und Entwickelungsgeschichte, Band 64, 1904. 



