Development of the Inverted Visceral Yolk Sac in Three Species of Caviids (Rodentia, Caviomorpha, Caviidae)

• Published in: Placenta (Eastbourne) Vol. 29; no. 8; pp. 748 - 752
• Main Authors: Miglino, M.A, Franciolli, A.L.R, de Oliveira, M.F, Ambrósio, C.E, Bonatelli, M, Machado, M.R.F, Mess, A
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.08.2008; Elsevier
• Subjects: Animal model; Animals; Biological and medical sciences; Capsule; Embryology: invertebrates and vertebrates. Teratology; Evolution; Female; Fetomaternal exchange; Fundamental and applied biological sciences. Psychology; Guinea pig; Internal Medicine; Maternal-Fetal Exchange - physiology; Models, Biological; Obstetrics and Gynecology; Placentation - physiology; Pregnancy; Pregnancy, Animal; Rodentia - physiology; Viscera - embryology; Viscera - ultrastructure; Yolk Sac - growth & development; Yolk Sac - ultrastructure; Animal model; Evolution; Capsule; Guinea pig; Fetomaternal exchange; Development; Yolk sac; Vertebrata; Mammalia; Rodentia
• ISSN: 0143-4004; 1532-3102
• DOI: 10.1016/j.placenta.2008.05.007

Abstract Guinea pig related rodents possess numerous derived placental characters. We attempt to identify diversity within the visceral yolk sac and its association with the chorioallantoic placenta in three species of caviids, two of them possessing a capsule formed by the decidua that covers the chorioallantoic placenta. The results verify that in early pregnancy all three species have an inverted yolk sac placenta. In advanced pregnancy the species differ: Galea spixii , as representative without a capsule, bear a yolk sac in apposition to the chorioallantoic placenta with signs of exchange activity until term. Galea is similar to other caviomorphs in this respect. In Dasyprocta leporina and Cuniculus paca , the representatives possessing a capsule, the yolk sac endoderm lacks signs of substance exchange. Evidently, the presence of a capsule prevents such an interaction. The variations established here must be considered if animal models for human placentation are required which have restricted access to the chorioallantoic placenta from the outside.