Home Education AUAUniversity Education Products & Resources Pathology for Urologists Normal Histology and Important Histo-anatomic Structures Testicular Appendages

Testicular Appendages

Image A

Image B

Appendix testis (Hydatid of Morgagni)

  • Present in >90% of testis, usually at the anterior-superior aspect beneath the epididymis head.
  • "Fan-shaped" appendage attached to the tunica vaginalis surrounded by columnar epithelium (image A).
  • Torsion may occur due to its pedunculated nature.
  • Represents the blind cranial end of Müllerian (paramesonephric) duct remnant.

Image C

Image D

Appendix epididymis

  • Present in >30% of testis, often at the superior aspect of epididymis head (image B) & (image C).
  • Cystic structure lined by columnar epithelium and filled with serous fluid (image D).
  • Subject to torsion.
  • Represents the blind cranial end of the Wolffian (mesonephric) duct remnant.
  • Torsion of testicular appendages result to bluish discoloration at the superior aspect of the testicle (blue-dot sign), but present in only 1/5 of patients.