Subplacental development in Galea spixii

Abstract

Animal models are essential to understand healthy human placentation. Guinea pig related rodents became on focus for such purposes. In particular, processes of trophoblast invasion are similar. The latter is associated with a specialized area, the subplacenta. Since previous results showed differences between the guinea pig and its close relative Galea spixii, we aimed to study subplacental development with more detail. We investigated 16 pregnant females of 14 to 55 days of gestation by means of histology, morphometrics, immunohistochemistry and electron microscopy. The overlap between the fetomaternal blood systems resulted as intimate, suggesting some exchange processes. Proliferation was revealed by three independent methods, being most active in early and mid-gestation, which was in accordance to former results. Though degeneration of tissues took place, the subplacenta was maintained towards term with access to the fetal vascularization, supporting a hypothesis about the release of substances to the fetal unit in advanced gestation. In contrast to other species, the extraplacental trophoblast showed a shift from syncytial streamers to giant cells during mid-gestation. Views on placentation in caviomorphs were influenced by the guinea pig, but our data supported recent studies that the subplacenta had a much greater placidity. In regard to subplacental grow, degeneration and likely also exchange processes, Galea and other species showed a more basal pattern of caviomorphs than the guinea pig. Such differences should be considered, when choosing most adequate animal models for special purposes in comparison to human placentation.

Morphology of the major salivary glands of Spix's Yellow‐Toothed Cavys (Galea spixii Wagler, 1831)

“…The animals were euthanized according to the methodology described by Bezerra et al (2018), with a pre‐anaesthetic association of xylazine hydrochloride (Xilazin® 2% – 1 mg/kg −1 ) and ketamine hydrochloride (Quetamina® 10% – 15 mg/kg −1 ). After 10 min, thiopental (Tiopental sódico® 1 g‐25 mg/kg −1 ) was administered intravenously.…”

The comparative aspects of hystricomorph subplacenta: potential endocrine organ

“…Some species within the Hystricomorph and Lagomorph sub-orders of the Rodentia have a specialized structure within their placentas, called a subplacenta [ 14 – 18 ], that is unusual among mammals. The structure is represented by zone of chorionic ectoderm, which is located in the central excavation of the placenta and is limited to the area of decidualization [ 19 ].…”

“…It is presumed that the subplacenta plays an important, specialized role during pregnancy in hystricomorph rodents [ 18 , 24 – 26 ]. However, despite the fact that this structure has been investigated in numerous morphological studies, there is a dearth of information in the literature in regard to the functions of this unusual placental structure.…”