The changes in the distribution of intravenously administered colloidal ink in splenectomized rabbits may be interpreted somewhat as follows: The removal of the spleen throws an increased amount of ink into the other hematopoietic organs and the lung and liver. While we should expect the liver or the bone marrow to compensate for the loss of the spleen and to take up this ink and remove it from the circulation, that is not the case. The lungs appear to play the chief part in the process, slowly passing on the removed material, contained in macrophages, to the liver, or retaining these ink-laden cells in their tissues and capillaries. By an increase in the capillary endothelium and by a process of engorgement of the capillaries with cells presumably derived therefrom, the lungs remove by far the greater part of the foreign material that has been introduced into the circulation.
At the same time there is an increase in the number of ink-bearing macrophages in the lymphatics and capillaries of the lung, indicating that these cells are entering the circulation and the lymph stream (Fig. 8). The only organ where they lodge in any quantities, outside of the peribronchial lymph nodes, is the liver, the sinusoids of which contain an increasing number of macrophages as time goes on. It is possible that these cells are destroyed in the sinusoids and the carbon transferred to the liver epithelium; there is evidence to support this assumption. After the lungs, the liver comes next in degree of intensity of pigmentation; the bone marrow contains far less than either of these organs.
