undulating membrane
noun
un·du·lat·ing membrane
| \ ˈən-jə-ˌlāt-iŋ-, ˈən-d(y)ə-
\
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Medical Definition of undulating membrane
: a vibratile cytoplasmic membrane:
a
: a lateral expansion of the plasma membrane in some flagellates that is usually associated with a flagellum
b
: a row of laterally fused long cilia associated in many ciliates with the oral structures