purchased from Japan SLC (Hamamatsu, Japan) and maintained on a commercial diet (CE-2,
Nihon CLEA, ) and mated in our animal facility. All mice had free access to food and tap
water and housed on sterilized chaw-chips in 0.5µm filter-cleaned air,
but not under specific pathogen free conditions, in a temperature-controlled room (25 ±
1°C) with 12 h of light per day. Both sexes of mice were used, because there was no sex
difference in the susceptibility for induction of AIG [26 (link)]. The day of birth was taken as day 0 of age. Three-day-old mice were
thymectomized as previously described [10 (link)].
Briefly, the sternum of infants was cut vertically from the salivary glands to the third
rib. Thymic lobes were removed by vacuum suction, and the chest cavity was closed. The
chest cavities of all animals were analyzed when the mice were sacrificed, and mice having
residual thymi were excluded from the experiments. The diagnosis of AIG was made
serologically and histologically when sacrificed, generally at twelve weeks of age for NTx
mice, when the disease development is almost completed (data not shown). All animal
experiments were performed according to the Guidance for Animal Experiments of Niigata
University.