Fig. 7. Ultrastructural analysis of the organ of Corti at E 18.5 using transmission electron microscopy (TEM). (A,C) Gfi1 wild-type mice. (B,D) Gfi1-null mice. (A,B) An overview of the outer hair cell. (C,D) The same outer hair cells as in A,B at a higher magnification. Double arrowheads indicate stereocilli of the wild-type outer hair cell, while single arrowheads indicate the blebbing seen in the mutant hair cell. Note the shrinkage of the cell body in the mutant outer hair cell. The mutant hair cell also contains vacuoles (asterisk). There is no detectable difference between wild-type and mutant hair cell mitochondria.