Dinâmica da inversão do saco vitelino em preás (Galea spixii Wagler, 1831)

Abstract

Pesq. Vet. Bras. 33(8) 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.INDEX TERMS: Galea, Galea spixii, yolk sac, visceral endoderm, parietal endoderm, inversion.

Origin and distribution of the brachial plexus in the Spix's yellow-toothed cavy (Galea spixii Wagler, 1831) (Rodentia, Caviidae)

“…The literature on the Spix's yellow-toothed cavy is restricted to studies on vascularisation (Oliveira et al 2011;Original Paper Veterinarni Medicina, 61, 2016 (6): 337-343 doi: 10.17221/206/2015-VETMED Oliveira et al 2012a;Oliveira et al 2013), placentation (Oliveira et al 2012b;Vale et al 2013) and reproduction (Santos et al 2012), whereas studies on the nervous system are limited to the lumbosacral plexus (Oliveira et al 2010;Oliveira et al 2014). The study of the morphology of species found in the wild is assuming growing importance, especially of those species with zootechnical potential or biological value, as is the case with Galea spixii, a rodent of great importance, since their meat is used as a source of animal protein for poor people or even more broadly owing to cultural habits in the north-eastern part of Brazil.…”

Characterization of epididymal sperm from Spix's yellow‐toothed cavies (Galea spixii Wagler, 1831) recovered by different methods

“…After 15 min, we induced anaesthesia with 50 mg/kg sodium thiopental (Thiopental; Cristalia, São Paulo, SP, Brazil) IV and euthanized the animals with 1 mL/kg potassium chloride IV (Vale et al . ). Immediately, we opened the abdomen and recovered the testis (including the epididymis and proximal vas deferens ).…”

Subplacental development in Galea spixii

“…In the latter, illustrations of subplacental structures focus on early ontogeny until day 12, whereas older stages are only superficially described (Oliveira et al 2008). Moreover, the length of gestation in the prea is variable and recent data indicated that it is about 55 to 60 days in animals from our breeding facilities (Vale 2011) and not 48 days as was assumed for former placental studies (Oliveira et al 2008(Oliveira et al , 2012b. Thus, real near term conditions of the subplacenta are absent in the literature (Oliveira et al 2008).…”