In vivo microscopy (IVM) provides a valuable method for studying the histophysiology of the living liver. The method allows observation of living cells in the intact organ of an anesthetized animal with an undisturbed microcirculation, at a magnification and a resolution comparable to normal light microscopy of sectioned material. Due to the absence of preparative procedures, the image differs substantially from histological sections, but it has the advantage of providing us with a reference preparation free of artifacts. In the case of the liver, we have the opportunity to observe directly such details as bile capillaries, intracellular fat droplets, lysosomes, nucleoli and different types of sinusoidal cells and blood cells.
By using epifluorescence, it is possible to visualize the phagocytosis of 0.8 μm fluorescent latex (or other) particles by Kupffer cells, to observe fluorescing substances such as FITC labeled asialofetuin during the process of endocytosis and intracellular transport in parenchymal cells, and to study the behavior of specific cell types such as white blood cells which stain specifically with acridine orange.
It might be expected that in the very near future, the application of modern techniques based on processing TV images, such as image intensifying, averaging, filtering, integrating, gating and others will tremendously improve the possibilities of IVM and bring it to the level of observing and following single molecules, such as FITC labelled peptide hormones and other probes, at the cellular level
