Ultrastructural neuropathology in murine trisomy 16 hippocampal grafts.

Trisomy 21, Down syndrome individuals demonstrate Alzheimer's disease-associated neuropathology at post mortem. The amyloid precursor protein, one of the pathological proteins is encoded for on chromosome 21. Mouse chromosome 16 is syntenic to human chromosome 21 for the region spanning the amyloid gene. We have previously reported the appearance of Alzheimer's disease-associated neuropathological proteins in cortical grafts derived from Trisomy 16 mice at 4-6 months survival. This paper reports the ultrastructural observations of large and multiple deposits of intracellular lipofuscin within these trisomic grafts at 12 months survival along with increased numbers of free ribosomes, extended Golgi apparatus and endoplasmic reticulum, membrane degeneration and abnormal axonal profiles. Similar but less severe neuro-degeneration is occasionally observed within 18-month-old normal, mouse hippocampal tissue and rarely observed in age-matched control grafts.