tunica vaginalis

https://doi.org/10.1351/goldbook.11332

Membranous sheath, derived from the peritoneum, surrounding the testis and epididymis.

Source:
PAC, 2016, 88, 713. (Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)) on page 816 [Terms] [Paper]