Testis

Q: What structure forms the mediastinum testis?

The mediastinum testis (mediastinum testis) is formed by a thickening of the tunica albuginea that projects deeply into the interior of the organ, acting as a central core. From the mediastinum, testicular septa (septula testis) radiate toward the periphery, dividing the parenchyma into approximately 250 lobules (lobuli testis).

Q: Where do the tubules of the rete testis empty?

The tubules of the rete testis (rete testis) open into the efferent ductules (ductuli efferentes). From the rete testis, 12–15 efferent ductules emerge externally. Their initial straight segments lie within the testis at the exit from the mediastinum, while their main convoluted and longer portion forms the head of the epididymis.

Q: Where is the epididymis located?

The epididymis (epididymis) is located strictly along the posterior border (margo posterior) of the gland.

Q: What layers are distinguished in the tunica vaginalis?

The tunica vaginalis (tunica vaginalis testis) consists of two layers: the visceral and parietal plates (lamina visceralis et parietalis).

Q: How are the testicular lobules formed?

The lobules (lobuli testis) are formed by septa that extend inward from the surrounding tunica albuginea.

For medical students2 min readUpdated 2026-10-10

The testis is a paired male reproductive gland located within the scrotum. The organ has a characteristic oval shape, slightly flattened laterally, and contains a complex internal system of tubules covered by dense connective tissue tunics.

Organ typePaired reproductive gland

LocationLocated in the scrotum

CoveringsCovered by tunica albuginea and tunica vaginalis

Relation to epididymisEpididymis lies along the posterior border

External Structure and Landmarks

Anatomically, the gland is oval-shaped and laterally compressed. To properly orient the organ, several key anatomical structures are defined.

External landmarks:

Surfaces: medial and lateral surfaces (facies medialis et lateralis).
Borders: anterior and posterior borders (margo anterior et posterior). Notably, the epididymis lies precisely along the posterior border.
Poles (extremities): superior and inferior poles (extremitas superior et inferior).

Coverings of the Organ

Externally, the gland is reliably protected by a system of coverings that maintain its shape and structural integrity.

The primary framework is formed by the tunica albuginea (tunica albuginea testis). Superficial to it lies the tunica vaginalis (tunica vaginalis testis). The latter has a complex structure consisting of two layers that form a closed cavity:

The visceral layer (lamina visceralis), closely fused to the organ.
The parietal layer (lamina parietalis), located more superficially.

Internal Structure and Tubular Pathway

The internal structure of the gland is strictly lobular. This architecture is formed by connective tissue septa extending inward from the dense tunica albuginea, dividing the parenchyma into individual testicular lobules (lobuli testis).

Inside each lobule lies a complex pathway of tubules:

Initially, seminiferous tubules convoluted (tubuli seminiferi contorti) are present.
Gradually, they straighten and transition into seminiferous tubules straight (tubuli seminiferi recti).
The straight tubules, in turn, merge to form a single rete testis (rete testis).

Mnemonic

To remember the sequence of internal pathways: "Convoluted paths always lead to Straight solutions on the Net" (Convoluted tubules → Straight tubules → Rete testis).

Frequently asked questions

What structure forms the mediastinum testis?

The mediastinum testis (mediastinum testis) is formed by a thickening of the tunica albuginea that projects deeply into the interior of the organ, acting as a central core. From the mediastinum, testicular septa (septula testis) radiate toward the periphery, dividing the parenchyma into approximately 250 lobules (lobuli testis).

Where do the tubules of the rete testis empty?

The tubules of the rete testis (rete testis) open into the efferent ductules (ductuli efferentes). From the rete testis, 12–15 efferent ductules emerge externally. Their initial straight segments lie within the testis at the exit from the mediastinum, while their main convoluted and longer portion forms the head of the epididymis.

Which arteries supply the testis with blood?

Blood supply to the testis is provided by the testicular artery (a. testicularis) and the cremasteric artery (a. cremasterica).

Where does venous drainage from the testis occur?

Venous drainage from the testis occurs via the pampiniform plexus (plexus pampiniformis), which then drains into the testicular vein.

Right testicular vein (v. testicularis dextra) drains directly into the inferior vena cava (v. cava inferior).
Left testicular vein (v. testicularis sinistra) drains into the left renal vein (v. renalis sinistra).

Which coverings directly overlie the testicular parenchyma?

The testicular parenchyma is directly covered by its own layered tunics:

Tunica albuginea (tunica albuginea) — a fibrous capsule enclosing the seminiferous tubules, located deep to the visceral layer of the tunica vaginalis.
Tunica vaginalis testis (tunica vaginalis testis) — covers most of the organ and consists of a visceral layer (lamina visceralis) and a parietal layer (lamina parietalis).

Where is the epididymis located?

The epididymis (epididymis) is located strictly along the posterior border (margo posterior) of the gland.

What layers are distinguished in the tunica vaginalis?

The tunica vaginalis (tunica vaginalis testis) consists of two layers: the visceral and parietal plates (lamina visceralis et parietalis).

How are the testicular lobules formed?

The lobules (lobuli testis) are formed by septa that extend inward from the surrounding tunica albuginea.

Go deeper

Detailed structure of the epididymis
Histological structure of convoluted seminiferous tubules
Topography of the rete testis and its connections
Mechanisms of formation of the tunica vaginalis layers