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

Favaron PO, Carter AM, Ambrósio CE, Morini AC, Mess AM, de Oliveira MF, Miglino MA - Reprod. Biol. Endocrinol. (2011)

Bottom Line: Abundant maternal uNK cells with positive response to PAS, vimentin and DBA-lectin were found in the decidua.The general aspect of the fetal membranes in Sigmodontinae resembled that found in other cricetid rodents.Glycogen cells were found to invade the decidua but we did not identify trophoblast in the walls of the deeper decidual arteries.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Surgery, School of Veterinary Medicine, University of Sao Paulo, Sao Paulo, Brazil.

ABSTRACT

Background: Sigmodontinae, known as "New World rats and mice," is a large subfamily of Cricetidae for which we herein provide the first comprehensive investigation of the placenta.

Methods: Placentas of various gestational ages ranging from early pregnancy to near term were obtained for five genera, i.e. Necromys, Euryoryzomys, Cerradomys, Hylaeamys, and Oligoryzomys. They were investigated by means of histology, immunohistochemistry, a proliferation marker, DBA-lectin staining and transmission electron microscopy.

Results: The chorioallantoic placenta was organized in a labyrinthine zone, spongy zone and decidua and an inverted yolk sac persisted until term. The chorioallantoic placenta was hemotrichorial. The interhemal barrier comprised fetal capillary endothelium and three layers of trophoblast, an outermost, cellular layer and two syncytial ones, with interspersed trophoblast giant cells (TGC). In addition, accumulations of TGC occurred below Reichert's membrane. The junctional zone contained syncytial trophoblast, proliferative cellular trophoblast, glycogen cells and TGC that were situated near to the maternal blood channels. In three of the genera, TGC were also accumulated in distinct areas at the placental periphery. PAS-positive glycogen cells derived from the junctional zone invaded the decidua. Abundant maternal uNK cells with positive response to PAS, vimentin and DBA-lectin were found in the decidua. The visceral yolk sac was completely inverted and villous.

Conclusion: The general aspect of the fetal membranes in Sigmodontinae resembled that found in other cricetid rodents. Compared to murid rodents there were larger numbers of giant cells and in some genera these were seen to congregate at the periphery of the placental disk. Glycogen cells were found to invade the decidua but we did not identify trophoblast in the walls of the deeper decidual arteries. In contrast these vessels were surrounded by large numbers of uNK cells. This survey of wild-trapped specimens from five genera is a useful starting point for the study of placentation in an important subfamily of South American rodents. We note, however, that some of these rodents can be captive bred and recommend that future studies focus on the study of time dated pregnancies.

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The junctional zone. (A) Necromys, early pregnancy (MAV/CEMAS 05). HE. The junctional zone (JZ) with simple structure facing towards the decidua. The border was not sharp with trophoblast derivatives (arrows) invading into the decidua. (B) Cerradomys, near term (MZUSP/APC 1157). The junctional zone had a folded structure arranged around the maternal blood channels (MBC). (C) Necromys, near term (MAV/CEMAS 02). TEM. Syncytial trophoblast (Syn TS) lined the maternal blood channels (MBC), associated with underlying cellular trophoblast (Cell TS). (D) Necromys, near term (MAV/CEMAS 02). TEM. In places the trophoblast separating the maternal blood spaces was represented only by a thin syncytial layer (arrow). (E) Necromys in early pregnancy (MAV/CEMAS 05). PCNA. Clustered groups of proliferating trophoblast cells (arrow) occurred in the junctional zone. (F) Necromys in mid gestation (MZUSP/APC 1246-1). PCNA. In more advanced stages, proliferating cells were widespread in the junctional zone. (G) Necromys in mid gestation (MZUSP/APC 1246-1). PCNA. Higher magnification. (H) Cerradomys, near term (MZUSP/APC 1157). HE. Among the spongiotrophoblast in the junctional zone, trophoblast giant cells (TGC) occurred. They were close to the maternal blood spaces and had large nuclei and prominent chromatin.
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Figure 4: The junctional zone. (A) Necromys, early pregnancy (MAV/CEMAS 05). HE. The junctional zone (JZ) with simple structure facing towards the decidua. The border was not sharp with trophoblast derivatives (arrows) invading into the decidua. (B) Cerradomys, near term (MZUSP/APC 1157). The junctional zone had a folded structure arranged around the maternal blood channels (MBC). (C) Necromys, near term (MAV/CEMAS 02). TEM. Syncytial trophoblast (Syn TS) lined the maternal blood channels (MBC), associated with underlying cellular trophoblast (Cell TS). (D) Necromys, near term (MAV/CEMAS 02). TEM. In places the trophoblast separating the maternal blood spaces was represented only by a thin syncytial layer (arrow). (E) Necromys in early pregnancy (MAV/CEMAS 05). PCNA. Clustered groups of proliferating trophoblast cells (arrow) occurred in the junctional zone. (F) Necromys in mid gestation (MZUSP/APC 1246-1). PCNA. In more advanced stages, proliferating cells were widespread in the junctional zone. (G) Necromys in mid gestation (MZUSP/APC 1246-1). PCNA. Higher magnification. (H) Cerradomys, near term (MZUSP/APC 1157). HE. Among the spongiotrophoblast in the junctional zone, trophoblast giant cells (TGC) occurred. They were close to the maternal blood spaces and had large nuclei and prominent chromatin.

Mentions: The junctional zone (Figures 4A,B) abutted the decidual region. It consisted largely of spongiotrophoblast. In most areas, both syncytial and cellular trophoblast were found (Figure 4C), but in some places only a thin syncytial layer was associated with the maternal blood spaces (Figure 4D), whereas in others there were trophoblast cells. The trophoblast cells were actively proliferative, as indicated by PCNA-staining. In early pregnancy, such proliferative trophoblast clustered as nests inside the junctional zone (Figure 4E), whereas it was more frequent and distributed throughout this region in more advanced pregnancies (Figures 4F,G). Moreover, trophoblast giant cells were dispersed within the junctional zone, closely associated with the maternal blood channels (Figures 4H). They had large nuclei and prominent chromatin. The largest amount of trophoblast giant cells inside the junctional zone was found in Oligoryzomys and Necromys, in both closely associated with the spongiotrophoblast. In the three other genera of sigmodontine rodents that had fewer trophoblast giant cells inside the junctional zone - Cerradomys, Hylaeamys and Euryoryzomys - trophoblast giant cells were found to be accumulated in distinct regions at the periphery of the placental disk (Figures 5A,B). All investigated genera of sigmodontine rodents possessed a continuous band of trophoblast giant cells, situated between the decidua and the junctional zone (Figure 5C). This band was connected to the region of accumulated trophoblast giant cells in the three above mentioned genera. The giant cells were mostly bi- or multinucleated in nature.


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

Favaron PO, Carter AM, Ambrósio CE, Morini AC, Mess AM, de Oliveira MF, Miglino MA - Reprod. Biol. Endocrinol. (2011)

The junctional zone. (A) Necromys, early pregnancy (MAV/CEMAS 05). HE. The junctional zone (JZ) with simple structure facing towards the decidua. The border was not sharp with trophoblast derivatives (arrows) invading into the decidua. (B) Cerradomys, near term (MZUSP/APC 1157). The junctional zone had a folded structure arranged around the maternal blood channels (MBC). (C) Necromys, near term (MAV/CEMAS 02). TEM. Syncytial trophoblast (Syn TS) lined the maternal blood channels (MBC), associated with underlying cellular trophoblast (Cell TS). (D) Necromys, near term (MAV/CEMAS 02). TEM. In places the trophoblast separating the maternal blood spaces was represented only by a thin syncytial layer (arrow). (E) Necromys in early pregnancy (MAV/CEMAS 05). PCNA. Clustered groups of proliferating trophoblast cells (arrow) occurred in the junctional zone. (F) Necromys in mid gestation (MZUSP/APC 1246-1). PCNA. In more advanced stages, proliferating cells were widespread in the junctional zone. (G) Necromys in mid gestation (MZUSP/APC 1246-1). PCNA. Higher magnification. (H) Cerradomys, near term (MZUSP/APC 1157). HE. Among the spongiotrophoblast in the junctional zone, trophoblast giant cells (TGC) occurred. They were close to the maternal blood spaces and had large nuclei and prominent chromatin.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
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Figure 4: The junctional zone. (A) Necromys, early pregnancy (MAV/CEMAS 05). HE. The junctional zone (JZ) with simple structure facing towards the decidua. The border was not sharp with trophoblast derivatives (arrows) invading into the decidua. (B) Cerradomys, near term (MZUSP/APC 1157). The junctional zone had a folded structure arranged around the maternal blood channels (MBC). (C) Necromys, near term (MAV/CEMAS 02). TEM. Syncytial trophoblast (Syn TS) lined the maternal blood channels (MBC), associated with underlying cellular trophoblast (Cell TS). (D) Necromys, near term (MAV/CEMAS 02). TEM. In places the trophoblast separating the maternal blood spaces was represented only by a thin syncytial layer (arrow). (E) Necromys in early pregnancy (MAV/CEMAS 05). PCNA. Clustered groups of proliferating trophoblast cells (arrow) occurred in the junctional zone. (F) Necromys in mid gestation (MZUSP/APC 1246-1). PCNA. In more advanced stages, proliferating cells were widespread in the junctional zone. (G) Necromys in mid gestation (MZUSP/APC 1246-1). PCNA. Higher magnification. (H) Cerradomys, near term (MZUSP/APC 1157). HE. Among the spongiotrophoblast in the junctional zone, trophoblast giant cells (TGC) occurred. They were close to the maternal blood spaces and had large nuclei and prominent chromatin.
Mentions: The junctional zone (Figures 4A,B) abutted the decidual region. It consisted largely of spongiotrophoblast. In most areas, both syncytial and cellular trophoblast were found (Figure 4C), but in some places only a thin syncytial layer was associated with the maternal blood spaces (Figure 4D), whereas in others there were trophoblast cells. The trophoblast cells were actively proliferative, as indicated by PCNA-staining. In early pregnancy, such proliferative trophoblast clustered as nests inside the junctional zone (Figure 4E), whereas it was more frequent and distributed throughout this region in more advanced pregnancies (Figures 4F,G). Moreover, trophoblast giant cells were dispersed within the junctional zone, closely associated with the maternal blood channels (Figures 4H). They had large nuclei and prominent chromatin. The largest amount of trophoblast giant cells inside the junctional zone was found in Oligoryzomys and Necromys, in both closely associated with the spongiotrophoblast. In the three other genera of sigmodontine rodents that had fewer trophoblast giant cells inside the junctional zone - Cerradomys, Hylaeamys and Euryoryzomys - trophoblast giant cells were found to be accumulated in distinct regions at the periphery of the placental disk (Figures 5A,B). All investigated genera of sigmodontine rodents possessed a continuous band of trophoblast giant cells, situated between the decidua and the junctional zone (Figure 5C). This band was connected to the region of accumulated trophoblast giant cells in the three above mentioned genera. The giant cells were mostly bi- or multinucleated in nature.

Bottom Line: Abundant maternal uNK cells with positive response to PAS, vimentin and DBA-lectin were found in the decidua.The general aspect of the fetal membranes in Sigmodontinae resembled that found in other cricetid rodents.Glycogen cells were found to invade the decidua but we did not identify trophoblast in the walls of the deeper decidual arteries.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Surgery, School of Veterinary Medicine, University of Sao Paulo, Sao Paulo, Brazil.

ABSTRACT

Background: Sigmodontinae, known as "New World rats and mice," is a large subfamily of Cricetidae for which we herein provide the first comprehensive investigation of the placenta.

Methods: Placentas of various gestational ages ranging from early pregnancy to near term were obtained for five genera, i.e. Necromys, Euryoryzomys, Cerradomys, Hylaeamys, and Oligoryzomys. They were investigated by means of histology, immunohistochemistry, a proliferation marker, DBA-lectin staining and transmission electron microscopy.

Results: The chorioallantoic placenta was organized in a labyrinthine zone, spongy zone and decidua and an inverted yolk sac persisted until term. The chorioallantoic placenta was hemotrichorial. The interhemal barrier comprised fetal capillary endothelium and three layers of trophoblast, an outermost, cellular layer and two syncytial ones, with interspersed trophoblast giant cells (TGC). In addition, accumulations of TGC occurred below Reichert's membrane. The junctional zone contained syncytial trophoblast, proliferative cellular trophoblast, glycogen cells and TGC that were situated near to the maternal blood channels. In three of the genera, TGC were also accumulated in distinct areas at the placental periphery. PAS-positive glycogen cells derived from the junctional zone invaded the decidua. Abundant maternal uNK cells with positive response to PAS, vimentin and DBA-lectin were found in the decidua. The visceral yolk sac was completely inverted and villous.

Conclusion: The general aspect of the fetal membranes in Sigmodontinae resembled that found in other cricetid rodents. Compared to murid rodents there were larger numbers of giant cells and in some genera these were seen to congregate at the periphery of the placental disk. Glycogen cells were found to invade the decidua but we did not identify trophoblast in the walls of the deeper decidual arteries. In contrast these vessels were surrounded by large numbers of uNK cells. This survey of wild-trapped specimens from five genera is a useful starting point for the study of placentation in an important subfamily of South American rodents. We note, however, that some of these rodents can be captive bred and recommend that future studies focus on the study of time dated pregnancies.

Show MeSH
Related in: MedlinePlus