Plains vizcacha females are able to ovulate up to 800 oocytes per estrus cycle. However, just 10-12 embryos are implanted and only two of them, those located nearest the cervix, are gestated to term. Between 26 and 70 days post-coitum, a constitutive resorption occurs from the embryos located proximal to the ovary, extending progressively toward those distally implanted. Our previous studies on the dynamics of gestation in L. maximus, led us to hypothesize some kind of placental and nutritional insufficiency as the basis for the resorption process. We analyzed histology and arterial architecture of the reproductive tract in pregnant and non-pregnant females. Uterine horns are irrigated through the uterine artery, a branch of the internal iliac artery, in an ascending way from the cervix; segmental arteries irrigating the embryo vesicles become thinner as they approach the ovary. Contrast solution administered during angiographies accumulated in the placenta of embryos closest to cervix. Thus, blood stream favors the embryos nearest the cervix, indicating a gradual nutritional deficiency of those closest to the ovary. Besides, placenta becomes calcified early, at mid-gestation, during the resorption process. Finally, the detection of specialized endothelial venules and inflammatory cells suggest the concurrent participation of immunological processes in embryo vesicles undergoing resorption.

中文翻译：

---

营养缺乏和胎盘钙化是怀孕的南美平原 vizcacha, Lagostomus maximus (Rodentia, Caviomorpha) 的组成性选择性胚胎丢失的基础

平原 vizcacha 雌性能够在每个发情周期排卵多达 800 个卵母细胞。然而，只有 10 到 12 个胚胎被植入，其中只有两个，即最靠近子宫颈的胚胎，能够怀孕到足月。在性交后 26 至 70 天之间，位于卵巢近端的胚胎发生组成性吸收，逐渐向远侧植入的胚胎延伸。我们之前对巨乳杆菌妊娠动力学的研究使我们假设某种胎盘和营养不足是吸收过程的基础。我们分析了怀孕和未怀孕女性生殖道的组织学和动脉结构。子宫角通过子宫动脉（髂内动脉的一个分支）从子宫颈以上升的方式灌注；当它们接近卵巢时，灌溉胚胎囊泡的节段动脉变得更细。在血管造影期间施用的造影剂在最靠近子宫颈的胚胎胎盘中积累。因此，血流有利于最靠近子宫颈的胚胎，表明最靠近卵巢的胚胎逐渐缺乏营养。此外，胎盘在吸收过程中在妊娠中期早期钙化。最后，特化内皮微静脉和炎症细胞的检测表明免疫过程同时参与了经历吸收的胚胎囊泡。表明最接近卵巢的人逐渐缺乏营养。此外，胎盘在吸收过程中在妊娠中期早期钙化。最后，特化内皮微静脉和炎症细胞的检测表明免疫过程同时参与了经历吸收的胚胎囊泡。表明最接近卵巢的人逐渐缺乏营养。此外，胎盘在吸收过程中在妊娠中期早期钙化。最后，特化内皮微静脉和炎症细胞的检测表明免疫过程同时参与了经历吸收的胚胎囊泡。