Localisation of alphafetoprotein (AFP) in murine teratocarcinoma

Solid tumours with histopathological characteristics of teratocarcinoma (generally presenting the structures of nervous origin) were induced in the mouse by subcutaneous inoculation with murine embryonal carcinoma (EC) cells of line PCC4-azal. An indirect immunoperoxidase technique using anti-mouse AFP antibodies was applied for the localization of the protein on paraffin sections of tissue fixed with acetic acid-ethanol. The PCC4-azal EC cells were AFP negative in vitro. In the solid tumours, the immature embryonal or fetal components (i. e. tubes or cysts mimicking the development of the neural tube) and the groups of neuroepithelial cells arranged in more or less differentiating structures (pseudotubes, cluters) were AFP positive; on the contrary, cells of the same differentiated neuroepithelial type, but lacking recognizable tissue architecture, were AFP negative. Mature, adult components were AFP negative. Undifferentiated cancer components, whether structured or not, were AFP negative. These results suggest that the intracellular presence of AFP requires a minimum degree of both cell differentiation and tissue organization.