Terminal differentiation of growth hormone (GH)-producing cells is severely disrupted in the pre-tumoural pituitary of the embryonic ACP mouse model. Double immunostaining with either β-catenin antibody (green) or terminal differentiation markers (red) on 18.5 dpc WT or Hesx1Cre/+/Ctnnb1+/lox(ex3) pituitary sections. Numbers of somatotrophs (GH-positive cells) (A) but not melanotrophs or corticotrophs (ACTH-positive cells) (B) are drastically reduced in the mouse ACP model relative to the control. Note that β-catenin-accumulating cell clusters do not express GH or ACTH (merge image). Bright fluorescent cells are red blood cells. Reproduced, with permission, from Gaston-Massuet C, Andoniadou CL, Signore M, Jayakody SA, Charolidi N, Kyeyune R, Vernay B, Jacques TS, Taketo MM, Le Tissier P, et al. (2011) Increased Wingless (Wnt) signaling in pituitary progenitor/stem cells gives rise to pituitary tumors in mice and humans. PNAS 108 11482–11487.
