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Figure 2 | Reproductive Biology and Endocrinology

Figure 2

From: Placentation in Sigmodontinae: a rodent taxon native to South America

Figure 2

Main regions of the chorioallantoic placenta. (A) Cerradomys, near term (MZUSP/APC 1177-1). HE. Trophoblast layers separated maternal blood channels (MBC) and fetal capillaries in the labyrinth; the latter with intact endothelium (arrows). The placental barrier varied, possessing very thin areas and some thicker regions that included sinusoid trophoblast giant cells (arrowheads). (B) Necromys, near term (MAV/CEMAS 01). Immunohistochemistry for cytokeratin. In contrast to the labyrinth, the junctional zone did not possess fetal vessels. The maternal blood channels in this area were associated with trophoblast. (C) Necromys in mid gestation (MZUSP/APC 1140). Immunohistochemistry for vimentin showed positive response for the fetal blood vessels (arrow) in the labyrinth (LAB), indicating an intact endothelium. In the visceral yolk sac (VYS) mesoderm was stained. In contrast, the maternal blood system of the labyrinth and junctional zone (JZ) lack endothelium, resulting in the vimentin-negative response of the junctional zone. In the decidua (D), maternal cells of mesenchymal origin were stained (arrow heads). (D) Necromys in mid gestation (MZUSP/APC 1140). Higher magnification of the labyrinth. Fetal vessels (arrow) ran inside the trophoblastic (vimentin-negative) layers that lined the maternal blood channels.

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