A group of cells labeled by the activity of the otp ECR6 enhancer project to the pituitary. A-D, Costaining of RFP with Avp (A) or Oxt (C) as typical hypophysiotropic cell types shows a high degree of overlap of fibers reaching the pituitary (magnified views in B and D). E, Costaining of RFP with Avp and Oxt combined (magnified view in F). G, Costaining with ACTH as a pituitary marker confirms the dense RFP bundles as part of the pituitary (magnified view in H). Abbreviations: r, rostral; l, lateral. Scale bars: 100 μm.