The comparative aspects of hystricomorph subplacenta: potential endocrine organ

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

The main evolutionary milestone in the oviparity-viviparity transition is placentation. The placenta is an organ with great morphological diversity among eutherians. The expression of different glycosidic residues (Gr) in the near-term placenta constitutes its glycotype. In this study, the expression of different Gr was determined by lectin histochemistry in early, midterm, and near-term placentas of the plains viscacha (Lagostomus maximus), a caviomorph rodent with the highest poliovulatory rate and embryonic resorption rate among eutherians. Besides, a matrix with the expression of each Gr in the exchange trophoblast of viscacha and other eutherians was constructed to map and infer phylogenetic and evolutionary relationships. Between early, midterm, and near-term placentas, variations in the pattern expression of Gr were observed. The glycotype of the near-term placenta is composed of a high diversity of Gr. Reconstruction of the ancestral state for each Gr present in the near-term placenta showed a diverse scenario: some sugars were common to the species of Placentalia included in this study. In the analyzed species with synepitheliochorial and epitheliochorial placentas, no differential glycosylation patterns between them were observed. In species with invasive placentas, such as the endotheliochorial placentas of Carnivora, some common Gr were detected among them, while others were species-specific. In species with hemochorial placenta, the same Gr are shared. Particularly, in the viscacha greater differences with species of the Hominidae and even Muridae families were observed. Nevertheless, greater similarities with other caviomorph rodents were detected. Placental glycotype of each species constitutes an excellent tool to achieve phylogenetic and evolutionary inferences among eutherians.

Reproductive Technologies Used in Female Neo-Tropical Hystricomorphic Rodents

This is the second of two literature reviews that focuses on the female reproductive anatomy and reproductive technologies used in selected neo-tropical hystricomorphic rodents. The rodents chosen included the agouti (Dasyprocta leporina), the capybara (Hydrochoerus hydrochaeris), and the paca (Cuniculus paca). Over seventy references were used, spanning the years 1919–2021. Knowledge of the reproductive tract is important in understanding any unique features, which may affect the use of reproductive technologies. Some unique characteristics common to these species included the presence of a vaginal closure membrane and a lobulated placenta with a vascular sub-placenta. The capybara had hyperpigmentation of the vagina that was unique to each individual, while the agouti and paca had accessory corpora lutea, in addition to the main one. Some reproductive technologies have been used, with attempts at estrous induction and synchronization taking place within the past five years. Even though most work has been done over the past twenty years, there is still a dearth of information.