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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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DBA-lectin staining in Cerradomys in mid gestation (MZUSP/APC 1177). (A) Positively reacting cells in the decidua that were usually in close association with maternal blood vessels. (B) They possessed large amounts of granules and represented mature uNK cells. (C) DBA-lectin staining also marked cells inside the labyrinth, particularly the endothelium of the fetal capillaries (arrow). (D) The same at higher magnification. (E) The visceral yolk sac epithelium was stained by DBA-lectin.
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Figure 9: DBA-lectin staining in Cerradomys in mid gestation (MZUSP/APC 1177). (A) Positively reacting cells in the decidua that were usually in close association with maternal blood vessels. (B) They possessed large amounts of granules and represented mature uNK cells. (C) DBA-lectin staining also marked cells inside the labyrinth, particularly the endothelium of the fetal capillaries (arrow). (D) The same at higher magnification. (E) The visceral yolk sac epithelium was stained by DBA-lectin.

Mentions: The uterine spiral arteries entered the placenta in the decidual region (Figure 7A). As indicated by immunohistochemistry for vimentin, the mesometrial arteries possessed an intact endothelium (Figure 7B). In contrast, the endothelium of the maternal vessels near the placental disk was not completely intact. Remnants of the endothelium were detected by using vimentin staining (Figure 7C). These findings suggested that the process of trophoblast invasion was restricted to regions adjacent to the placenta. Closely associated with the maternal arteries of the decidua in all species examined, there was a large amount of both smaller and larger cells that possessed PAS-positive granules (Figures 8A,B). Such cells were often found closely grouped together. In some of these cells more than one nucleus was present (Figure 8B). In addition to PAS, these cells reacted positively for vimentin (Figure 8C), indicating that they were derived from mesenchymal tissue and thus must be of maternal origin. They were identified as uterine natural killer cells (uNK cells). In early pregnancy such PAS-positive and vimentin-positive uNK cells were also found near the developing placental disk (Figure 8D). Cells associated with the maternal arteries were not cytokeratin-positive (Figure 8E). The data once more supported their identification as uNK cells and indicated the restricted mode of trophoblast invasion into the decidua. In detail, the uNK cells mostly had large nuclei with irregular or spherical shape and some glycogen granules (Figure 8F). Using DBA-lectin staining (a phenotypic marker for uNK cells), we were able to detect positively reacting uNK cells associated with the blood vessels and inside the decidua (Figure 9A,B). However, DBA-lectin staining in sigmodontine rodents was not specific to uNK cells, marking also cells inside the labyrinth, the endothelium of the fetal capillaries in particular (Figures 9C,D), as well as the visceral yolk sac epithelium (Figure 9E).


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)

DBA-lectin staining in Cerradomys in mid gestation (MZUSP/APC 1177). (A) Positively reacting cells in the decidua that were usually in close association with maternal blood vessels. (B) They possessed large amounts of granules and represented mature uNK cells. (C) DBA-lectin staining also marked cells inside the labyrinth, particularly the endothelium of the fetal capillaries (arrow). (D) The same at higher magnification. (E) The visceral yolk sac epithelium was stained by DBA-lectin.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3094283&req=5

Figure 9: DBA-lectin staining in Cerradomys in mid gestation (MZUSP/APC 1177). (A) Positively reacting cells in the decidua that were usually in close association with maternal blood vessels. (B) They possessed large amounts of granules and represented mature uNK cells. (C) DBA-lectin staining also marked cells inside the labyrinth, particularly the endothelium of the fetal capillaries (arrow). (D) The same at higher magnification. (E) The visceral yolk sac epithelium was stained by DBA-lectin.
Mentions: The uterine spiral arteries entered the placenta in the decidual region (Figure 7A). As indicated by immunohistochemistry for vimentin, the mesometrial arteries possessed an intact endothelium (Figure 7B). In contrast, the endothelium of the maternal vessels near the placental disk was not completely intact. Remnants of the endothelium were detected by using vimentin staining (Figure 7C). These findings suggested that the process of trophoblast invasion was restricted to regions adjacent to the placenta. Closely associated with the maternal arteries of the decidua in all species examined, there was a large amount of both smaller and larger cells that possessed PAS-positive granules (Figures 8A,B). Such cells were often found closely grouped together. In some of these cells more than one nucleus was present (Figure 8B). In addition to PAS, these cells reacted positively for vimentin (Figure 8C), indicating that they were derived from mesenchymal tissue and thus must be of maternal origin. They were identified as uterine natural killer cells (uNK cells). In early pregnancy such PAS-positive and vimentin-positive uNK cells were also found near the developing placental disk (Figure 8D). Cells associated with the maternal arteries were not cytokeratin-positive (Figure 8E). The data once more supported their identification as uNK cells and indicated the restricted mode of trophoblast invasion into the decidua. In detail, the uNK cells mostly had large nuclei with irregular or spherical shape and some glycogen granules (Figure 8F). Using DBA-lectin staining (a phenotypic marker for uNK cells), we were able to detect positively reacting uNK cells associated with the blood vessels and inside the decidua (Figure 9A,B). However, DBA-lectin staining in sigmodontine rodents was not specific to uNK cells, marking also cells inside the labyrinth, the endothelium of the fetal capillaries in particular (Figures 9C,D), as well as the visceral yolk sac epithelium (Figure 9E).

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