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Body of epididymis

The body of the epididymis is the central and longest part of the epididymis, lying along the posterolateral aspect of the testis. It connects the head (caput) of the epididymis superiorly to the tail (cauda) inferiorly. It is composed of a highly convoluted duct (epididymal duct) that continues from the efferent ductules of the head and extends into the tail, forming a key site for sperm maturation and storage.

The body of the epididymis is an important landmark in scrotal anatomy and imaging, especially in the evaluation of infertility, infection, trauma, and tumors.

Synonyms

  • Corpus epididymis

  • Middle epididymis

  • Central portion of epididymis

Location and Structure

  • Location:

    • Lies along the posterolateral surface of the testis

    • Occupies the groove between the testis and the epididymal body

  • Structure:

    • Contains a long, coiled epididymal duct (up to several meters in length when uncoiled)

    • Surrounded by connective tissue and vascular plexus

    • Continuation of the epididymal head superiorly and continuous with the epididymal tail inferiorly

Relations

  • Anteriorly: Tunica vaginalis (visceral layer covering testis and epididymis)

  • Posteriorly: Scrotal wall and connective tissue septa

  • Medially: Testis parenchyma

  • Laterally: Epididymal connective tissue and fat planes

Function

  • Site of sperm maturation (acquiring motility and fertilizing ability)

  • Acts as a conduit for sperm transport from head to tail and then to vas deferens

  • Provides a storage reservoir for spermatozoa before ejaculation

  • Secretes proteins and glycoproteins that aid in sperm maturation

Clinical Significance

  • Epididymitis: Inflammation commonly involving the body and tail, often infectious in origin

  • Obstruction: May cause obstructive azoospermia and infertility

  • Cysts/spermatoceles: Frequently arise in body or tail, usually benign

  • Tumors: Rare, but can occur (e.g., adenomatoid tumor, sarcoma)

  • Trauma: Can be injured in scrotal trauma, often with hematoma formation

MRI Appearance

T1-weighted images:

  • Epididymal body shows low-to-intermediate signal intensity

  • Fat surrounding epididymis appears bright, outlining its contour

  • Hemorrhage or cystic changes may appear bright depending on composition

T2-weighted images:

  • Body of epididymis shows intermediate to mildly hyperintense signal

  • Fluid-filled cysts or spermatoceles show very bright signal intensity

  • Chronic fibrotic changes appear as dark areas

STIR (Short Tau Inversion Recovery):

  • Normal body shows intermediate to mildly hyperintense signal

  • Inflammation or edema demonstrates bright hyperintensity

  • Fat signal is suppressed, improving lesion detection

T1 Fat-Sat Post-Contrast:

  • Normal epididymal tissue enhances mildly and uniformly

  • Inflammatory changes show more intense, diffuse enhancement

  • Abscesses show rim enhancement with non-enhancing center

  • Tumors show variable heterogeneous enhancement

3D T2 SPACE / CISS:

  • Body of epididymis appears as an intermediate to mildly hyperintense tubular structure

  • Surrounded by bright fluid or fat, providing excellent delineation of ducts

  • Useful for detecting small cysts, ductal dilatation, or focal lesions

CT Appearance

Non-Contrast CT:

  • Body appears as a soft tissue density structure along the posterolateral testis

  • Surrounding fat provides contrast for localization

  • Hematomas may appear as hyperdense foci

Post-Contrast CT:

  • Normal epididymis enhances mildly

  • Inflammation shows diffuse or patchy enhancement

  • Abscess shows rim enhancement with central low attenuation

  • Tumors appear as enhancing soft tissue nodules

MRI images