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Septum of testis

The septum of the testis refers to the connective tissue partitions that extend inward from the tunica albuginea into the testicular parenchyma. These septa divide the testis into 200–300 lobules, each containing tightly coiled seminiferous tubules. The septa converge posteriorly at the mediastinum testis, which contains rete testis channels, blood vessels, lymphatics, and supporting connective tissue.

The septum plays a crucial role in providing internal support to the testis, maintaining lobular organization, and serving as conduits for vascular and lymphatic structures. It also has radiological significance in the evaluation of testicular pathology such as tumors, trauma, or infection.

Synonyms

  • Testicular septa

  • Septula testis

  • Connective tissue partitions of testis

Structure and Relations

  • Origin: Arises from the inner surface of the tunica albuginea

  • Course: Projects radially inward to the mediastinum testis

  • Convergence: Joins at the mediastinum testis located at the posterior border of the testis

  • Relations:

    • Laterally: Seminiferous tubules within lobules

    • Posteriorly: Mediastinum testis (rete testis, vessels, lymphatics)

    • Externally: Tunica albuginea enclosing the testis

Function

  • Provides structural framework for organization of testicular lobules

  • Acts as a supporting pathway for blood vessels, lymphatics, and ducts

  • Maintains segmentation of seminiferous tubules for efficient spermatogenesis

  • Supports internal integrity of the testis during contraction of cremasteric and dartos muscles

Clinical Significance

  • Important in testicular tumor imaging: tumors may distort or invade septa

  • Serves as a pathway for vascular spread of pathology within the testis

  • Can be a site of fibrosis or thickening in chronic orchitis or trauma

  • Visible distortion on imaging may indicate neoplasm, abscess, or hematoma

  • Helps radiologists distinguish between intratesticular and paratesticular lesions

MRI Appearance

T1-weighted images:

  • Septa appear as low-signal linear structures radiating toward the mediastinum

  • Fat surrounding vessels or hilum appears bright, highlighting the septa

T2-weighted images:

  • Septa remain low signal intensity relative to seminiferous tubules

  • Mediastinum appears as a central low-signal band posteriorly

STIR (Short Tau Inversion Recovery):

  • Septa show dark signal intensity

  • Pathological thickening (inflammation or tumor infiltration) may appear bright

T1 Fat-Sat Post-Contrast:

  • Normal septa enhance minimally or not at all

  • Infiltrated septa (tumor, orchitis, abscess wall) show linear or nodular enhancement

3D T2 SPACE / CISS:

  • Septa visible as thin hypointense linear structures within bright testicular parenchyma

  • Provides excellent delineation of mediastinum and lobular organization

CT Appearance

Non-Contrast CT:

  • Septa usually not directly visualized

  • Appears indirectly as subtle fibrous striations in testis surrounded by uniform soft tissue density

  • Calcifications within septa may be seen in chronic inflammation or tumor

Post-Contrast CT:

  • Septa enhance faintly or not at all

  • Pathological involvement (tumor, infection) may appear as enhancing linear or nodular thickening radiating to mediastinum

MRI image

septum of the testis mri axial anatomy image-img-00000-00000