Table 4. Studies of PrPres and gray matter vacuolation in scrapie-infected anchorless PrP tg44+/− mice with C57BL/6 embryonic brain grafts.

	Recipient host genotype
	PrPnull	Tg44+/−
Number of mice	7	10
Number of grafts	20	31
Grafts with PrPres	20	25
Grafts with gray matter vacuoles	18	22
Adjacent host gray matter with PrPres	0	20
Adjacent host gray matter with vacuoles	0	0

Anchorless PrP tg44+/− mice or PrPnull (−/−) adult mice were grafted with 12–14 d embryonic brain tissue from C57BL/6 mice expressing normal anchored PrP and green fluorescent protein (GFP) [25], as described in the Methods. One month after grafting, mice were infected with scrapie by IC inoculation. Mice were euthanized at various times from 135–511 dpi, and brain tissue sections were examined by H&E staining and immunohistochemical staining for GFP and PrPres.