The mediastinum testis is a network of fibrous connective tissue that extends from the upper to near the lower extremity of the testis, and is wider above than below.
Numerous imperfect septa (trabeculæ) are given off from its front and sides, which radiate toward the surface of the organ and are attached to the tunica albuginea.
They divide the interior of the organ into a number of incomplete spaces, called lobules. These are somewhat cone-shaped, being broad at their bases at the surface of the gland, and becoming narrower as they converge to the mediastinum.
The mediastinum supports the rete testis and blood vessels of the testis in their passage to and from the substance of the gland.