Abstract
From the pathological study of four cases of splenic anemia showing partial or complete obstruction of splenic or portal veins due to old thrombophlebitis, the writer was led to believe that the splenic enlargement (fibrosis) and the clinical picture of splenic anemia might be produced experimentally in animals. During the last two years he has carried on a series of observations upon dogs whose splenic veins had been ligated at varying distances from that organ. Briefly, the results have been as follows:
In dogs examined from one week to three months after the operation the spleen was found greatly enlarged, firm and dark in color. This enlargement reached its extreme about four weeks after the ligation.
In dogs examined after three months the spleen was found to be diminished in size, paler and firmer. In those examined one year after ligation of the splenic veins the organ was found to be greatly atrophic and fibroid, in two cases completely separated into small islands or lobes of splenic tissue, each lobe having a separate vein running into the gastro-splenic omentum, and anastomosing with veins from the stomach. Such a collateral circulation was found established in all cases.
All animals with splenic atrophy become very fat. Hyperplasia of the prevertebral hemolymph nodes was noted. There was a slight anemia, the hemoglobin being reduced to a greater degree than the red blood cells. No lasting changes in the white cells were observed. Microscopically the spleen showed a lymphoid atrophy, relative increase of stroma and excessive pigmentation.
These experiments would indicate that obstruction of the splenic veins of dogs by ligation is not followed by a fibroid hyperplasia of the spleen but by a partial atrophy. A more or less complete venous collateral circulation is always produced.
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