Or bugs, which leave these red or blue stains.

或虫子，会留下这些红色或蓝色的污渍。

He wiped away the blue stain above his lip with the back of his arm, then let out the tiniest burp.

他用胳膊背擦去嘴唇上方的蓝色污渍， 然后打了个最小的嗝。

Here's a classic histology image of cirrhotic tissue, this clump of cells in the middle is the regenerative nodule, and these blue stains surrounding it are the bands of protein from the process of fibrosis.

这张典型的肝硬化组织的组织学图像，中间圈出的部分这堆细胞生结节，包围生结节的蓝色的区域肝脏纤维化过程中形成的蛋白质束。