Viability under the testis capsule of inner cell masses isolated from TOr/TOr mouse embryos

Single inner cell masses (ICM) isolated by immunosurgery from late blastocysts were able to develop into benign teratomas under the testis capsule after 1 month with a frequency of 76%. This technique was used to examine viability and developmental potency of embryos homozygous for the TOr mutation. The number of teratomas formed by the ICMs derived from TOr/+ X TOr/+ crosses was consistent with what is expected if TOr/TOr ICMs did not produce them. After ectopic culture for a short period, presumed TOr/TOr ICMs gave rise to abnormal spherical structures resembling embryonic parts of the mutant embryos at the egg cylinder stage. These results suggest that TOr/TOr ICMs have greatly decreased competency for developmental potency.