The murky interiors of the pitcher have very smooth walls with a waxy texture.

笼内视野昏暗，蜡质的内壁十分光滑。

The lungs also start to release a small peptide called bradykinin which constricts the smooth muscle wall of the ductus arteriosus and helps the process along.

肺也开始释放缓激肽，收缩动脉导管的平滑肌，有助于动脉导管闭合。