•  The testis (testicle) is the primary reproductive organ of the male. It is suspended in the scrotum by the dartos muscle and spermatic cords.

•  Each oval-shaped testicle is approximately 4-5 cm long, 3 cm deep, and 2.5 cm wide.

•  They lie obliquely within the scrotum, with the superior poles directed anterolaterally.

•  The anterior and lateral surfaces are convex, while the attachment of the spermatic cord makes the posterior surface straighter.

•  The testis has, at its superior pole, a small appendix. This is an embryological remnant, similar to the appendix of the epididymis.

•  The testis is concerned with the manufacture of sperm cells and hormones, including testosterone. 

•   Sperm cells are produced in the linings of the coiled seminiferous tubules that are found within the lobe of the testis. 

•  The seminiferous tubules converge on the epididymis. From here, the sperm cells are transported to the epididymis for storage until ejaculation. The interstitial tissue between the seminiferous tubules secretes androgens.

•  The testicular capsule that consists of three layers surrounds the testis. The layers are the tunica vaginalis, tunica albuginea, and the tunica vasculosa.

Tunica Vaginalis

•  The tunica vaginalis is the outer layer of the testicular capsule. 

•  This develops as the processus vaginalis of the peritoneum and precedes the testis in its descent from the abdomen to the scrotum. 

•  The proximal part then disappears, leaving the tunica as a closed, double-layered sac around the testis.

Inner layer

•  The inner layer of this sac, in contact with the testis, is the visceral tunica.

•  This covers the anterior and lateral aspects and the poles of the testis, but not the posterior aspect. 

•  On the medial side of the posterior aspect of the testis it is reflected anteriorly onto the parietal layer. 

•  Posterolaterally, it covers the medial side of the epididymis and lines the epididymal sinus. 

•  It is reflected forwards as the parietal layer from the posterior border of the epididymis.

•  At the poles, the visceral layer reflects as the parietal, covering the head of the epididymis superiorly. 

Outer layer

•  The outer layer of this sac, in contact with the internal surface of the scrotum, is the parietal tunica. 

•  This extends inferior to the testis before ascending anteromedially to the spermatic cord.

•  The inner surface is smooth and moist, allowing it to slide over the visceral layer beneath it. 

Tunica Albuginea

•  The tunica albuginea is the middle layer of the testicular capsule. 

•  This is a very tough, blue-white capsule composed mainly of bundles of collagen fibers. It is covered by the visceral layer of the tunica vaginalis, except at the head and tail of the epididymis and at the entry point of the vessels and nerves on the posterior aspect of the testis.

•  At the posterior border of the testis, the tunica albuginea projects into the testis as a thick, vertically oriented septum called the mediastinum testis. It is widest at the superior pole of the testis, from where it reaches almost as far as the inferior pole, but it is not complete.

•  From the sides and front of the mediastinum testis, several septa radiate out to the deep surface of the tunica albuginea. This divides the testis into cone-shaped lobules, with their bases at the surface of the testis and their apices at the mediastinum.

Tunica Vasculosa

•  The tunica vasculosa is the inner layer of the testicular capsule. This consists of a plexus of blood vessels and loose connective tissue that covers the internal surface of the tunica albuginea and the septa between the testicular lobules.

Blood Supply

•   Testicular artery.

Venous Drainage

•  Testicular veins.

Nerve Supply

•  T11-T12 via the renal and aortic autonomic plexuses.


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