Prenatal development in Lagostomus maximus (Rodentia, Chinchillidae): A unique case among eutherian mammals of physiological embryonic death

Abstract

Embryonic death followed by resorption is a conserved process in mammals. Among the polyovular species, Lagostomus maximus (plains viscacha) constitutes a model of early and physiological embryonic death, since out of a total of 10–12 implants, 8–10 are resorbed during early/intermediate gestation, surviving are only the most caudal implantations of each uterine horn. This regular reproductive event is unique to this species, but many characteristics of the implantations during the early gestation of L. maximus, when embryonic death processes begin are unknown. The aim of the present work was to analyze the implantation sites of this species using morphological, morphometric, histochemical, lectinhistochemical, and immunohistochemical techniques to infer the possible causes of this event. Macroscopically, the length and width of the implantation sites significantly increased in a craniocaudal direction. Histochemically, the implantation sites did not differ in the expression of glycoconjugates and glycosidic residues. Furthermore, no variations were observed in cell renewal, hormone receptor expression, and decidualization. Both the glandular and vascular areas of the implantation sites significantly increased in the craniocaudal axis. Some necrotic cells and an inflammatory response with a predominance of lymphocytes and fibrin were observed in the cranial and middle but not in the caudal implantation sites. We conclude that signs of embryonic death and resorption are already observed in the early gestation of L. maximus. Our results reaffirm the hypothesis that postulates the key potential role of uterine glands and blood vessels in the gestation of the species, with emphasis on embryonic death. This pattern of embryonic death in L. maximus makes this species an unconventional mammalian model, which adds to the peculiarities of polyovulation (200–800 oocytes/estrus) and hemochorial placentation.

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

“…This particularity in the hormonal dynamics during the gestation of the plains viscacha could explain the variations in the histochemical expression of the different glycosidic residues for each of the components of the placenta. In the ovaries, oviducts, uterus, and vagina of the plains viscacha, variations in glycosylation patterns were also observed in nonpregnant females and at different gestational times (Acuña et al, 2020, 2021; Flamini et al, 2009, 2012, 2014, 2019).…”

“…Its knowledge allows the understanding of variations in unusual pregnancy events, such as the physiological early embryonic death (Fiorentino et al, 2018;Díaz et al, 2017;Dorsch et al, 2019), and the phylogenetic relationships between clades (Jones et al, 2007;Klisch et al, 2010). The plains viscacha (Lagostomus maximus -Chinchillidae), a caviomorph rodent, is a suitable model for studying both aspects (Acuña et al, 2020(Acuña et al, , 2021(Acuña et al, , 2022aFlamini et al, 2019Flamini et al, , 2020. Although different characteristics of the ontogeny of the hemochorial placenta of L. maximus (Figure 1) are known (Acuña et al, 2022b;Barbeito et al, 2021;Flamini et al, 2011Flamini et al, , 2020Giacchino et al, 2020), its glycotype is unknown.…”

Natural life cycle of Versteria cuja (Taeniidae) in Argentina and histopathology of metacestodiasis in intermediate hosts

“…1 were incubated separately with the primary antibodies pancytokeratin (Pk, dilution 1/250, Agilent, Z0622) to identify epithelial origin cells, and proliferating cell nuclear antigen (PCNA, 1/3000 dilution, Sigma-Aldrich, SAB2701819) to identify proliferating cells. All techniques used were based on standardized protocols of the Laboratorio de Histología y Embriología Descriptiva, Experimental y Comparada, Facultad de Ciencias Veterinarias , Universidad Nacional de La Plata (Acuña et al ., 2021 ).…”