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Year 2008 - Volume 28, Number 05
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Aspectos morfológicos do saco vitelino em dois roedores da subordem Hystricomorpha: paca (Agouti paca) e cutia (Dasyprocta aguti), p.253-259
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ABSTRACT.- Conceição R.A., Ambrósio C.E., Martins D.S., Carvalho A.F., Franciolli A.L.R., Machado M.R.F., Oliveira M.F. & Miglino M.A. 2008. [Morphological aspects of yolk sac from rodents of Hystricomorpha subordem: paca (Agouti paca) and agouti (Dasyprocta aguti).] Aspectos morfológicos do saco vitelino em dois roedores da subordem Hystricomorpha: paca (Agouti paca) e cutia (Dasyprocta aguti). Pesquisa Veterinária Brasileira 28(5):253-259. Setor de Anatomia dos Animais Domésticos e Silvestres, Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia. Universidade de São Paulo, Cidade Universitária, Av. Prof. Dr. Orlando Marques de Paiva 87, São Paulo, SP 05508-900, Brazil. E-mail: ceambrosio@usp.br
The study aimed to characterize gross and microscopic features of the yolk sac in paca (Agouti paca) and agouti (Dasyprocta aguti) in early gestation. Fragments of the yolk sac of 3 paca and 3 agouti fetuses at early gestation were taken and processed for histological and ultrastructural analyses. Gross features of the vitelline placenta in both species showed its insertion over the main placenta surface and projections to the embryos/fetuses. Microscopically, the vitelline placenta was constituted by endoderm epithelium and mesenchyme, in which vitelline vessels are abundant. The ultrastructure of the samples showed that the visceral yolk sac of the paca was formed by endodermic cells with nuclei in the median region, and that the visceral yolk sac of the agouti was formed by nuclei arranged apically; other characteristic was the large number of mitochondrias, eletrodense vesicles with microvilosities We conclude that (1) the vitelline placenta of the two species presents insertion in the surface of the main placenta; (2) the vitelline placenta of paca rests on the Reichert’s membrane, whereas the agouti vitelline placenta does not have this membrane; (3) the chorion and allantoic are fusioned; and (4) the chorioallantoic placenta and the yolk sac in both species are reversed and vascularized. |
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