Cerebral pathology in immunodeficient gnotobiotic laboratory mice.

-/animals, the pineal gland was considerably reduced in mass. Only in the latter strain was a strong pineal hypertrophy in the form of a benign tumor present in ca. 50% of the animals. A possible sequence of events leading to hydrocephalus is discussed. Endogenous vertically transmitted facultative pathogens, active in the immunocompromised animals, probably play a primary etiological role. The results show that caution is needed in planning immunobiological studies on the B10.PL and B10.PL-derived mice, and possibly other strains not examined for possible neuropathological changes.