ACTH expression in the pituitary. Immunolabeled ACTH positive cells are red. A. Anterior pituitary section from a Lifr +/- untreated control mouse. The pars intermedia (pi) appears as a band to the left that contains many immunolabeled cells. The pars distalis (pd) contains scattered ACTH immuno-positive cells. B. Anterior pituitary from a Lifr -/- littermate to the pup in panel A. C. Anterior pituitary section from a Lifr +/+ pup where the mother received RU486 on E16.5 and E17.5. ACTH immunolabeling is increased relative to panel A. D. An anterior pituitary section from a RU486 treated Lifr -/- littermate of the pup in panel C. All sections were processed by immunohistochemistry at the same time. The size bar indicates 200 μm.