Laboratorio de Histología y Embriología Descriptiva, Experimental y Comparada, Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, Buenos Aires, Argentina.
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
J Morphol. 2023 Mar;284(3):e21566. doi: 10.1002/jmor.21566.
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.
卵生性到胎生性转变的主要进化里程碑是胎盘形成。胎盘是真兽类中形态多样性巨大的器官。在接近分娩的胎盘上，不同糖苷残基（Gr）的表达构成了其糖型。在这项研究中，通过凝集素组织化学方法确定了平原兔尾鼠（Lagostomus maximus）早期、中期和接近分娩期胎盘上不同 Gr 的表达，平原兔尾鼠是真兽类中具有最高多排卵率和胚胎吸收率的有袋目啮齿动物。此外，还构建了兔尾鼠和其他真兽类交换滋养层中每种 Gr 表达的基质，以绘制和推断系统发育和进化关系。在早期、中期和接近分娩期的胎盘之间，观察到 Gr 表达模式的变化。接近分娩期胎盘的糖型由高度多样化的 Gr 组成。对出现在接近分娩期胎盘上的每个 Gr 的祖先状态进行重建，结果显示出多样化的情况：一些糖在包括在本研究中的胎盘类物种中是共同的。在所分析的具有合胞上皮胎盘和上皮胎盘的物种中，没有观察到它们之间的差异糖基化模式。在具有侵袭性胎盘的物种中，如食肉目动物的内皮胎盘，在它们之间检测到一些共同的 Gr，而其他则是物种特异性的。在具有血绒毛膜胎盘的物种中，共享相同的 Gr。特别是，在兔尾鼠中，与灵长目和甚至鼠科的物种观察到更大的差异。然而，与其他有袋目啮齿动物的相似性更大。每个物种的胎盘糖型构成了在真兽类中进行系统发育和进化推断的极好工具。
