periplast

詳細解釋：

per.i.plast

n.（名詞）
An outer layer surrounding the cell membrane of certain microorganisms, such as a spirochete.
質膜：某些微生物，如螺旋體，包圍細胞壁的外層膜
A cell membrane or cell wall.
一種細胞膜或細胞壁