n.下水道，阴沟，泄殖腔

The cloaca is a common structure in many lower animals, serving as their primary excretory and reproductive organ.
克洛阿卡是许多低等动物共有的结构，是它们的主要排泄和生殖器官。
In vertebrates, the cloaca eventually splits into separate systems for urination, defecation, and reproduction.
在脊椎动物中，克洛阿卡最终会分化为单独的排尿、排便和生殖系统。
The embryo of a frog develops a cloaca before it undergoes metamorphosis into an adult.
青蛙胚胎在变态发育成成体前形成克洛阿卡。
The cloaca is an important concept in comparative anatomy, helping scientists understand evolutionary relationships among species.
克洛阿卡是比较解剖学中的重要概念，帮助科学家理解物种间的进化关系。
Some ancient organisms, like the coelacanth, had a single cloaca that served multiple functions.
有些古老的生物，如肺鱼，有一个单一的克洛阿卡，负责多种功能。
In some invertebrates, the opening to the cloaca is called the anus orifice.
对于一些无脊椎动物，克洛阿卡的开口被称为肛门。
The formation of a cloaca in vertebrates marks a key stage in the development of the nervous system.
脊椎动物克洛阿卡的形成标志着神经系统发育的重要阶段。
The presence of a cloaca in vertebrates contrasts with the separate systems found in most mammals.
脊椎动物有克洛阿卡与大多数哺乳动物的独立系统形成了对比。
Scientists have studied the evolution of the cloaca in reptiles to better comprehend their early ancestors.
科学家通过研究爬行动物的克洛阿卡来更好地理解它们的早期祖先。
In medical contexts, the term "urocloaca" refers to the embryonic fusion of the urinary and intestinal tracts before they become separate organs.
在医学上，术语"urocloaca"指的是在泌尿道和肠道分离之前，它们在胚胎期的融合状态。