Table 1.

XL169- and RO072- derived chimaeric male Breeding Results

male XL169 mice analyzeda	total # offspring produced by males analyzed	agouti offspring producedb	heterozygotes produced
low-medium percentage chimaeric malesc	494	162	6
high percentage chimaeric malesd	0	N/Ae	N/A
male RO072 mice analyzed	total # offspring produced by males analyzed	agouti offspring produced	heterozygotes produced
low-medium percentage chimaeric malesf	301	46	8
high percentage chimaeric malesg	75	11	2

Notes:

a) chimaerism was determined by coat color (agouti): over 90% chimaeric is classified as "high", below 90% as "low-medium".

b) agouti offspring can have the Odf2^+/+ genotype (phenotypically wt mice) or the Odf2^+/- genotype (heterozygote). In agouti offspring one Odf2 allele derives from the C57Bl/6 background and the other allele (either the normal Odf2 allele, or the genetrap-interrupted Odf2 allele) derives from the XL169 ES background

c) 13 males of low-medium % chimaerism were analyzed by breeding

d) 5 males of high % chimaerism were analyzed by breeding

e) N/A = not applicable.

f) 7 males of low-medium % chimaerism were analyzed by breeding

g) 2 males of high % chimaerism were analyzed by breeding