The spleen, an immune organ, initiates immune reactions to blood-borne antigens and filtering out foreign material and spent circulating cells. It comprises at least 2 primary cellular compartments: the white pulp with its “periarteriolar lymphatic sheath, marginal zone and follicle” and the red pulp with its “reticular fibers, reticular cells, and associated macrophages”. These compartments have different vascular and cellular architecture.

Looking at mouse spleen after the infusion of a 10% IPFD 5% F68 emulsion at 100CC/kg, 55 days post, I had expected spleen to be completely packed with macrophages full of IPFD particles and yet I dont think (this is an estimate) that the volume density of crystals would be any more than 1-3% of the whole spleen.  It is also clear that white pulp is pretty much devoid of cells with IPFD crystals, and IPFD crystals were pretty much limited to the red pulp. A quick look says that megakaryocytes don’t take up IPFD, red cell production, mitotic cells dont have IPFD inclusions (or much of it) that areas that are most likely to have cells with IPFD inclusions are around blood vessels.  I have spleen tissue from infusion of many other prerfluorochemical emulsions…. spleens with IPFD are going to have to go to the back burner till I can figure out some fun stuff about liver.

It looks like IPFD does exit the liver after a period of 200 days or so, the crystals in the liver macrophages have largely disappeared, but what is left in the wake of the crystals is a host of cells that are in the interstitial and periportal spaces which should not really be there. The macrophages that were multinuclear remain that way with many dark areas (organelles) likely remnants of the massive lysosomal structures that were present during the IPFD occupation.