ON THE WIDESPREAD OCCURRENCE OF RETICULAR FIBRILS 

 PRODUCED BY CAPILLARY ENDOTHELIUM, 



By GEOKGE W. CORNER. 



In adding his contribution to those here gathered, the writer deems it most 

 appropriate to present a study which not only took origin during the course of an 

 investigation suggested by Dr. Mall, but which led back into another field that 

 he had made particularly his own, and in which his interest and advice would have 

 been most eagerly sought, had a happier providence allowed. 



In one of his best-known and most important papers Dr. Mall, in 1891, 

 announced his discovery that the framework of many organs and tissues of the 

 mammalian body is composed neither of white fibrous nor of yellow elastic con- 

 nective tissue, but of a third type of supporting substance composed of fine inter- 

 lacing fibrils which not only differ from the white fibers in appearance, but are more 

 resistant to both acid and alkaline solvents and are not so readily attacked by 

 digestive ferments. He applied the name "reticulum" to the new tissue because 

 the fibrils of the lymph-nodes, already bearing this name, were the first which he 

 found to present the characteristics just mentioned. The supporting fibrils of the 

 spleen, gastric and intestinal mucosa, liver, lung, thyroid, heart-muscle, the base- 

 ment membranes of the testis, and the entire supporting structure of the kidney, 

 including the basement-membranes, were all demonstrated in this first paper to 

 be of the same type. That the internal connective tissue of many other organs falls 

 in the same category was later shown in publications by various of Mall's pupils, 

 of which the most interesting in the present connection are those upon the corpus 

 luteum by J. G. Clark (1898), and the adrenal gland by J. M. Flint (1900). In 1902 

 Mall published his important account of the development of the connective tissues, 

 showing that in the intestine, and presumably in other organs, the reticular fibrils 

 are developed within the cytoplasm of the mesenchymal syncytium. 



To this last statement, however, he noted one striking exception. In the liver 

 the reticulum arises from von Kupffer's endothelial cells: 



"The observations upon the development of the reticulum of the liver are entirely 

 out of harmony with those of the development of connective tissue elsewhere. In all other 

 places the syncytium arises from the mesenchyme, but here it is from the endothelial 



lining of blood vessels The fibrils are in no way connected with the liver cells and 



true mesenchyme cells are not present at all." 



This discovery was confirmed by J. Kon in 1908. A denial by Madame Schum- 

 kow-Trubin (1909) would seem to be erroneous; the present writer's preparations 

 agree with the description of Mall and Kon. 



After the work of several investigators had proved the identity of the fibrils 

 shown in the liver by the digestion method with the "Gitterfasern" long since 



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