Male Reproductive System
Scrotum
Embryology
Around week six, genital swellings develop either side of the urethral folds and, under the influence of testicular androgen, become scrotal swellings, moving caudally from the inguinal region. The two swellings are separated by the scrotal septum.
Anatomy
The scrotal wall consists of six layers. From the outside in, these are the:
- Scrotal skin
- Dartos muscle
- External spermatic fascia
- Cremasteric muscle and fascia
- Internal spermatic fascia
- Parietal layer of the tunica vaginalis
The testis itself is covered by the visceral layer of the tunica vaginalis and the tunica albuginea, which is a tough fibrous layer that maintains the ovoid shape of the testis.
Epididymis
The epididymis measures 6-7 cm in length and is composed of a head (globus major), a body and a tail (globus minor).
The head is formed by 10-15 efferent ductules from the rete testis. It lies lateral to the superior pole of the testis and measures 10-12 mm in diameter.
The body lies adjacent to the posterolateral margin of the testis and normally measures <4 mm.
The tail is loosely attached to the lower pole of the testis, where it folds back on itself to ascend medial to the body, to become the vas deferens.
Vas and Spermatic Cord
Beginning at the lower part of the tail of the epididymis, the vas is initially a tortuous structure that straightens to ascend medial to the epididymis. At the upper pole of the testis, it continues as part of the spermatic cord into the inguinal canal, but separates from the rest of the cord at the internal inguinal ring.
The spermatic cord is formed of the three fascial layers picked up during descent of the testis through the inguinal canal. It also contains the testicular, cremasteric and deferential arteries, the pampiniform plexus of veins, lymphatics and the genital branch of the genitalfemoral nerve.