Fig. 4. Intragranular localization of SgIII, CPE and peptide hormones PRL and POMC. (A) WT mouse (WT) mammotropes, (B) Cpe^fat mouse (fat/fat) mammotropes, (C) WT corticotropes and (D) fat/fat mouse corticotropes. SgIII and CPE were visualized with 15 and 10 nm gold particles, respectively. PRL (A,B) and POMC-derived ACTH-containing peptides (C,D) were labeled with 5 nm gold particles. CPE observed in the WT mammotropes and corticotropes (A,C, respectively) was not found in the fat/fat mammotropes and corticotropes (B,D, respectively), although these ultrathin sections were immunostained with a less-diluted antibody to CPE (1:10 at dilution). By contrast, SgIII was detected as in Fig. 1. Note that anti-ACTH-antibody-reacting POMC-derived peptides are distributed from the peripheral to the intragranular region of the SGs (C,D). Bar, 100 nm.