Abstract：
The species Cuniculus paca is highly subject to predation, whether natural or anthropogenic, and the ability of species to withstand different levels of depredation depends directly on their reproductive dynamics. However, there is little literature on the developmental biology of this species, and so the aim of this paper was to describe the fetal development of the urinary tract of C. paca through morphological analysis. Twelve specimens with estimated gestational ages of between 75 and 157 days were used, divided into 3 groups. We found the urinary tract in pelvic-abdominal topography with macroscopic differentiation between the organs already present in the first ages studied; in addition, the microscopic structural pattern changed little between the groups. This evidence reinforces the precocial development of these individuals. RESEARCH HIGHLIGHTS: With the results obtained for development of urinary tract in Cuniculus paca reinforces the precocial development of these individuals. The urinary tract had pelvic-abdominal topography with macroscopic differentiation between the organs already present in the first ages studied. The microscopic structural pattern changed little between the groups. At all analyzed fetal ages, the cortical region of kidney was characterized by the presence of glomeruli arranged throughout the region, formed by capillary plexuses surrounded by a glomerular capsule. In addition, the cortical region also presented convoluted tubules with cubic epithelial tissue cells and a brush border. The presence of a developed macula densa was observed next to the glomeruli, suggesting the initial formation of the fetal juxtaglomerular apparatus.
摘要：
paca的物种高度受捕食，无论是自然的还是人为的，物种承受不同程度的掠夺的能力直接取决于它们的繁殖动态。然而,关于这个物种的发育生物学的文献很少，因此，本文的目的是通过形态学分析来描述胎儿尿道的发育。使用了12个估计胎龄在75到157天之间的样本，分为3组。我们发现骨盆-腹部地形图中的尿路在研究的最初年龄中已经存在的器官之间具有宏观差异；此外，组间微观结构模式变化不大。这些证据加强了这些个体的早熟发展。研究重点：通过获得的尿路发育结果，加强了这些个体的早熟发育。泌尿道具有骨盆-腹部地形图，在研究的第一个年龄中已经存在的器官之间具有宏观差异。组间微观结构模式变化不大。在所有分析的胎儿年龄中，肾脏的皮质区域的特点是肾小球的存在排列在整个区域，由肾小球囊包围的毛细血管丛形成。此外,皮质区域还呈现具有立方上皮组织细胞和刷状边界的曲折小管。在肾小球旁边观察到发育的黄斑的存在，提示胎儿球旁器官的初步形成。
