"In vivo" means "in the vital body". In vivo Immunology is to study immune system at individual body level with an aid of polychromatic immunostaining of tissue sections and light microscopy.
Download PDF: The microstructure of secondary lymphoid organs that support immune cell trafficking. Arch Histol Cytol 73:1-21, 2010.
In 1989, we developed the polychromatic immunostaining for CD antigens, specific antibody molecules, cell proliferation markers and other markers for up to 3 combinations (J. Leukoc. Biol. 68: 705-712, 2001). By this, we became able to study immune responses morphologically on tissue sections.
In vivo Veritas: Truth resides in the vital body and not in the test tube.