Immunohistochemical detection of leptin and leptin receptor in the pre-implantation uterus and inter-placental sections during pregnancy. Immunohistochemical localization of leptin (Lep; A, C) and leptin receptor (LepR; B, D) in pre-implantation and inter-placental uterine sections (Ut) during pregnancy. (A) Lep immunostaining at pre-implantation is present in the luminal epithelium (solid arrows) and in the superficial glands (open arrows); endothelial cells stain occasionally (thin arrow). The myometrium and deep uterine glands also show positive reaction for Lep (inset upper right); inset (lower left) indicates the isotype control for Lep. (B) LepR immunoreactivity in the Ut at pre-implantation is noted in the surface epithelium (solid arrows), and in the endometrial stroma close to the lumen (solid arrowheads). Superficial glands (open arrows) stain weakly, and the myometrium and deep uterine glands also show positive signals (inset upper right); inset (lower left) shows the isotype control for LepR. (C) Strong Lep staining is visible in the deep uterine glands at mid-gestation; stromal signals are also evident (solid arrowheads), while endothelial cells show sporadic, weak signals (thin arrows). (D) At mid-gestation, the epithelium of deep uterine glands has stronger LepR immunoreactivity than at pre-implantation. Stromal signals are still present (solid arrowheads), and signals are also found occasionally in the endothelium (thin arrows). DG: deep uterine glands, MY: myometrium.