tunic
US /ˈtuː.nɪk/
UK /ˈtuː.nɪk/

1.
2.
膜, 层
a part of an organ or other body structure that resembles a tunic in form or function.
:
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The tunica albuginea is a layer of connective tissue that surrounds the testes.
白膜是包围睾丸的结缔组织层。
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The smooth muscle layer of the intestine is called the tunica muscularis.
肠道的平滑肌层被称为肌层。