Transplacental Transfer of Iron in the Water Buffalo (Bubalus bubalis): Uteroferrin and Erythrophagocytosis

Abstract

The objectives of this investigation were to understand transplacental transport of iron by secreted uteroferrin (UF) and haemophagous areas of water buffalo placenta and clarify the role(s) of blood extravasation at the placental-maternal interface. Placentomes and interplacentomal region of 51 placentae at various stages of gestation were fixed, processed for light and transmission electron microscopy, histochemistry and immunohistochemistry. Haemophagous areas were present in placentomes collected between 4 and 10 months of pregnancy. Perl's reaction for ferric iron was negative in placentomes, but positive in endometrial glands. Positive staining for UF indicated areas in which it was being taken up by phagocytosis and/or fluid phase pinocytosis in areolae of the interplacentomal mesenchyme, with little staining in endometrial stroma. Imunohistochemistry detected UF in trophectoderm of haemophagous regions of placentomes and in other parts of the foetal villous tree, but the strongest immunostaining was in the epithelial cells and lumen of uterine glands. Ultrastructural analyses indicated that erythrophagocytosis was occurring and that erythrocytes were present inside cells of the chorion that also contained endocytic vesicles and caveolae. Results of this study indicate that both the haemophagous areas of placentomes and the areolae at the interface between chorion and endometrial glands are important sites for iron transfer from mother to foetal-placental tissues in buffalo throughout pregnancy.

ACP5 (Uteroferrin): Phylogeny of an Ancient and Conserved Gene Expressed in the Endometrium of Mammals1

“…In addition, ACP5 has been localized in the endometrial glandular epithelium of pregnant mares, ewes, and water buffalo [17][18][19]. All of these species exhibit an epitheliochorial or syndesmochorial type of placentation in which chorionic epithelium apposes, but does not invade, endometrial epithelium.…”

Ovine uterine space restriction alters placental transferrin receptor and fetal iron status during late pregnancy

“…However, virtually nothing is known about placental iron transfer in multifetal gestation and/or reduced uterine space. In mammals, iron transport to the fetus is accomplished by three recognized pathways: 1) iron-rich endometrial gland secretions; 2) endocytosis of transferrin (Tf)-bound iron through transferrin receptors (TfR); and 3) trophoblast ingestion of pooled maternal erythrocytes in the hemophagous zone (12-14). Although detailed mechanisms are not described in sheep, the ovine model confers the advantage of utilizing all three pathways for fetal iron acquisition (12).…”

Advances in flow cytometry in basic and applied equine andrology

“…4A; Wooding et al, 2000), endometrial glands secrete the iron-rich glycoprotein uteroferrin, which is taken up by the polarized trophoblast of the areolae. Recently, uptake of uteroferrin was also described in the water buffalo (Bubalus bubalis; Pereira et al, 2009). Although the uteroferrin gene (tartrate-resistant acid phosphatase type 5) is found in other mammals, its central role in fetal iron supply likely emerged in the ungulate lineage.…”