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tunica vaginalis testis

[văj′ə-nā′lĭs tĕs′tĭs]
n.
  1. The serous sheath of the testis and epididymis, derived from the peritoneum, and consisting of an outer and inner serous layer.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.