Because that's because each sac contains a cluster of alveoli, these tiny cavities lined with super thin, wet membranes made of simple squamous epithelium tissue.

因为这是因为每个囊包含一簇肺泡，这些微小的空腔内衬着由简单鳞状上皮组织制成的超薄湿膜。

We're not able to print complex organs just yet, but simpler tissues including blood vessels and tubes responsible for nutrient and waste exchange are already in our grasp.

我们尚未能打印出复杂的器官，但例如血管和负责交换营养和废物的管道这些较简单的组织已经在我们掌握之中。

But these studies at least give scientists hope that we could learn better methods for treating human conditions, like wound healing and regenerating simple tissues.

但这些研究至少让科学家们希望我们能够学习更好的方法来治疗人类疾病，比如伤口愈合和简单组织的再生。

The cool thing about this layer is that it contains the endothelium, which you may remember is made up of simple squamous epithelium tissue and is continuous with the lining of the heart.

这层最酷的地方是它包含内皮，你可能记得内皮是由简单的鳞状上皮组织组成的，并且与心脏内膜连续。