40 The Intralobular Framework of the Human Spleen 



of pancreatin and washed in water. The resulting specimens were 

 in some cases stained, imbedded and sectioned; in others immersed in 

 glycerin and studied with a low-power stereoscopic microscope. The 

 thick sections thus obtained afforded most instructive pictures in three 

 dimensions. 



Controls of the digested specimens were stained with orcein, Wei- 

 gert's elastic tissue stain, hasmatoxylin and eosin, and the connective 

 tissue stains of Mallory and Van Gieson. In searching for elastic 

 fibers within the lobule the so-called differential stains of Weigert, 

 Mallory and Unna-Tanzer were employed. 



Digested specimens were stained by immersing them in a five per 

 cent solution of the ammonio-sulphate of iron for 12-18 hours, and 

 subsequently removing them to a five per cent aqueous solution of 

 hsematoxylin for four hours. By difi!erentiating such specimens in a 

 one per cent solution of acetic acid a sharp and intense black stain was 

 obtained. Weigert's elastic tissue stain was also used to stain digested 

 specimens. 



Dilute aqueous solutions of potassium hydrate, acetic and hydro- 

 chloric acids were employed in testing and differentiating the connec- 

 tive tissues of the framework. 



DISCUSSION. 



By macerating and washing fresh human spleen tissue it is possible 

 to remove the parenchyma cells and expose a framework of blood- 

 vessels and anastomosing fibers that outlines the general form of the 

 specimen in all dimensions. This is the coarser framework of the 

 spleen formed by the trabeculse and is of imiform density throughout 

 the organ. Its meshes, incompletely marked off by the surrounding 

 fibers, average 20 microns in diameter and are the compartments occu- 

 pied by lobules. In a specimen thus prepared each compartment ap- 

 pears as a vacuole, its outline alone being indicated. 



If, however, spleen tissue be hardened in alcohol, thoroughly ex- 

 tracted with ether, and the parenchyma entirely removed by pancreatin 

 digestion without mechanical injury, there is preserved in addition to 

 the coarser framework a delicate network of fibrils within each indi- 

 vidual compartment — the intralobular framework. (Fig. 1, C.) 



The delicate fibrils composing the intralobular network vary from 

 1 to 5 microns in diameter. They branch and anastomose in all 

 directions to form a network with meshes from 16 to 40 microns 

 in diameter. The fibrils are directly continuous with those of 

 the coarser interlobular framework at the periphery of the lobule 



