单词tunica-submucosa
网络: 黏膜下层；粘膜下层
The wall of the alimentary canal is made up of two layers: tunica mucosa and tunica submucosa, lacking muscular layer except the esophagus.
消化道管壁由粘膜层和粘膜下层组成，除食道外缺乏肌层。
The wall of digestive tract is made up of four layers, which are the mucosa, tunica submucosa, muscularis and serosa.
消化道管壁由粘膜层、粘膜下层、肌层和浆膜层构成。