Fig. 6. Structural and ultrastructural analyses of the adrenal glands of Gata3 mutant mice. (A) Electron micrograph of wild-type E18.5 adrenal glands reveals the presence of numerous large secretory granules (arrowheads) that are characteristics of mature chromaffin cells, whereas E18.5 Gata3^-/- mutant adrenal glands (C) lack granules. (B) Tg^hDBH-G3 bred into the Gata3 mutant background restores typical chromaffin cell ultrastructure. Scale bar: 2 µm. (D-F). Anti-Sf1-negative chromaffin cells were abundant in wild-type and Tg-rescued Gata3 mutant mice, whereas a normal, centrally located adrenal medulla was never observed in pharmacologically rescued Gata3 mutant adrenal gland. The size of the adrenal cortex appears unaltered in the Gata3 mutant adrenal gland. Scale bars: 100 µm.