The comparative aspects of hystricomorph subplacenta: potential endocrine organ

Abstract

Background The placenta of hystricomorph rodents, lagomorphs and some primates includes an unusual structure, termed a subplacenta, which essentially consists of trophoblastic cells located deep to the central implantation site within the area of decidualization. It has been suggested that the subplacenta is functionally important, although considerable controversy remains on the issue. In this context, our objective was to compare the architecture and structure of the subplacentas of different hystricomorph species, to investigate the possibility that it is active in hormone synthesis. Methods In total, the placentas of 3 capybaras (Hydrochaeris hydrochaeris), 2 pacas (Agouti paca), 5 agoutis (Dasyprocta leporina), 5 rock cavies (Kerodon rupestris) and 3 guinea pigs (Cavia porcellus) at different stages of pregnancy (early, middle and near term) were used for gross and microscopic examination. This included the preparation of latex injection casts, immunohistochemistry for steroidogenic enzymes, scanning and transmission electron microscopy. Tissue steroid concentrations were also determined. Results The gross morphology and microvascular arrangement of the subplacentas were similar among the hystricomorphs studied including ultra-structural verification of cytotrophoblast and syncytiotrophoblast in all species. In guinea pigs, trophoblast cells exhibited characteristics consistent with intense metabolic and secretory activity in general. However, immuno-histochemical evidence also indicated that subplacental trophoblast expressed key steroidogenic enzymes, mainly in the chorionic villus region, consistent with tissue steroid concentrations. Conclusions The subplacentas within placentas of hystricomorph rodent species are structurally similar and, in guinea pigs, have potential for steroid hormone secretion from, at least the early stages of pregnancy.

Placental glycotype of the caviomorph rodent Lagostomus maximus and its evolution within Eutheria

“…In hystricognath rodents, progesterone circulates bound to a progesterone‐binding protein (Heap et al, 1981). The subplacenta, an organ with endocrine functions (Miglino et al, 2021), is thought to be the source of this glycoprotein (Rodrigues et al, 2006). In our study, we observed the labeling of different glycosidic residues in the trophoblastic cells of the subplacenta, which could be part of these glycoproteins.…”

Reproductive Technologies Used in Female Neo-Tropical Hystricomorphic Rodents

“…The author, however, did not obtain the expected results as no positive correlation was noted between the high estradiol levels and vaginal cytology [ 63 ]. Also, the placentation is characteristic of hystricomorphic rodents, i.e., contains a sub-placenta [ 64 ].…”