66 HISTIOTROPHIC NUTRITION AND IRON TRANSFER ACROSS THE MATERNO-FETAL INTERFACE IN NUCLEAR TRANSFER-DERIVED SOMATIC CATTLE CLONES

Abstract

The histiotrophic nutrition by the endometrial glands and the materno-fetal interface in the cloned cattle placenta were analyzed in order to investigate the iron transfer. Placentomes and intercaruncular region samples were recovered at term Caesarean delivery from 14 cloned cattle and 10 controls, fixed in 4% paraformaldehyde and 10% formaldehyde in PBS, processed and stained for light microscopy (hematoxylin-eosin, picrosirius, and Masson's trichrome), histochemistry [Perls, acid phosphatase and periodic acid Schiff (PAS) reactions], and immunohistochemistry (with rabbit anti-pig uteroferrin antibody because the uteroferrin is an iron transporter protein). In the controls we verified blood extravasations in the materno-fetal interface between the uterine and the trophoblast epithelium characterized by hemophagous areas with consequent erythrophagocytosis by the adjacent trophoblast. This content presented extravasated erythrocytes, plasm, cell debris, and cells in a probable apoptotic process. The Perls histochemical reactions that exposed the ferric iron in the placentomes were positive, as was the uteroferrin immunohistochemistry in the trophoblast cytoplasm and in other deep points in the placentomes. The histochemical reactions, demonstrating the acid phosphatase enzyme that detects the phagocytic activity, were positive in the mesenchyme and trophoblast, with a weak stain in an endometrial stroma. In the top of fetal villi, mainly in the binucleate cells, we visualized accumulations of PAS-positive secretions, indicating the presence of mucoid material. The uterine gland epithelium was columnar-type and in the gland lumina there were cell debris and PAS-positive mucoid secretions. We confirmed the reactivity of the uterine glands to the acid phosphatase enzyme and to the Perls reaction in the epithelium and in the gland lumina. The uteroferrin immunohistochemistry showed a strong stain in the cytoplasm of the endometrial glands cells and in the lumina. In the NT bovine placentae, the blood extravasations between uterine and trophoblast epithelium were aberrant. There was also the remodeling of the maternal connective tissue (endometrial stroma) in this area. We also demonstrated phagocytic uptake of uteroferrin by the trophoblast, although the histochemical and immunohistochemical reactions were weak in the trophoblast of the placentomes and in the endometrial glands of the intercaruncular region, when compared with the controls. The results obtained by the histochemistry and immunohistochemistry indicated that these sites of transfer substances from mother to fetus are very important in providing adequate nutrition to the fetus, key to a successful pregnancy in NT bovines.

This work was funded by FAPESP, Brazil.