Beyond the mucosa, there is smooth muscle followed by more connective tissue, and together, these two layers make up the submucosa and this is where the bronchial mucinous glands live.

黏膜层外是平滑肌细胞，之后是更多结缔组织，这两层共同组成粘膜下层，是黏液腺所在之处。

One measurement, typically done post-mortem, is called the Reid index, which is the ratio of the thickness of the bronchial mucinous glands, relative to the total thickness of the airway - from the epithelium to the cartilage.

雷德指数是一种检验标准，一般在尸检时进行，它是支气管黏液腺厚度与气道从上皮到软骨总厚度的比值。