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Year 2013 - Volume 33, Number 8
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Dynamics of yolk sac inversion in galea (Galea spixii Wagler, 1831), 33(8):1033-1040
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ABSTRACT.- Vale A.M., Oliveira G.B., Favaron P.O., Miglino M.A., Paula V.V., Silva A.R. & Oliveira M.F. 2013. [Dynamics of yolk sac inversion in galea (Galea spixii Wagler, 1831).] Dinâmica da inversão do saco vitelino em preás (Galea spixii Wagler, 1831). Pesquisa Veterinária Brasileira 33(8):1033-1040. Programa de Pós-Graduação em Ciência Animal, Universidade Federal Rural do Semi-Árido, BR 110 Km 47, Rodovia Presidente Costa e Silva s/n, Mossoró, RN 59625-900, Brazil. E-mail: andre_bioquimico@hotmail.com
The aim of this study was to study the time of yolk sac inversion as well as the dynamics resulting from this process in galea throughout pregnancy. For this, conventional histological techniques, scanning electron microscopy and transmission electron microscopy were used. Parietal and visceral endoderm delimiting the yolk sac cavity was observed at 12 days of pregnancy. The parietal endoderm was coating the fetal surface of the chorioallantoic placenta as well as delimiting the decidua capsularis area. This endoderm had prismatic format and were apart from the trophoblast by an enlarged Reichert’s membrane. The visceral endoderm had vitelline vessels and there were villi only in certain areas. At 14 days of pregnancy the yolk sac inversion was characterized by the degeneration of parietal endoderm and mural trophoblast, and also the gradual disappearance of the Reichert’s membrane. So it made the visceral endoderm establish an interface with the uterine epithelium. After the inversion, the parietal endoderm which remained intact was the one that rested on the chorioallantoic placenta surface. It presented cells with high columnar format and pseudostratified epithelium featured. The visceral endoderm presented many apical villi, especially in areas close to the chorioallantoic placenta. The continued development of the embryo and chorioallantoic placenta evidenced the emergence of an important apposition area between visceral and parietal endoderm. The yolk sac inversion represented an anatomical arrangement in favor of the embryo development as well as an evolutionary trait in this rodent species. |
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