Pathobiologic significance of the subcellular organelles of lepra cells.

The polar typ es of leprosy, tuberculoid and lepromatous, are eharacteri zed by two dif-ferent and well-defin ed form s of cellular resp0l1se (~fi). Tubereuloicl les ions consist of circumscribed granulom as made up of epithelioid cells which contain few leprosy bacilli. Lepromatous lesions, in contrast, are composed of diffuse aggregates of foamy macrophages ( Virehow cells ) laden with large numbers of bacteria and lipid debris. Epithelioid and Virchow cells constitute the two ext remes in the cytologic spectrum of leprosy. Electron microscopy has cmphasized the basic morphologic differences between the two cell types. The cytoplasm of epithclioid cclls is occupied by abundant mitochondria and a prominent ergastoplasmie reticulum (27) . There are no cytopl asmic components in epithelioid cells that differ significantly from the types of 01'ganellcs found in ordin ary macrophages. Virchow cell s, on the other hand, are packed with lcprosy bacilli which are frcquently fragmcnted and secm to be in a state of degeneration . The foamy appearance of thesc cells has been shown by electron microscopy to be due to the presence of large clear cytoplasmic vacuoles which have been referred to as "leprosy inclusions" (5) . The electron microscope has also revealed in lepromatous cells, an additional type of dense cytopl asmic organelle given the descriptive name of "opaque droplets' CG). These opaque droplets sometimes have a vesiculated or