Now that we've looked at the testis, we'll move on to see the pathway by which spermatazoa reach the urethra. We'll look at the ductus deferens and spermatic cord, the seminal vesicles and the ejaculatory duct.
The spermatic cord is the lifeline to the testis. It contains the testicular blood vessels and the ductus deferens. To see these structures, we'll divide the coverings of the spermatic cord. Here are the covering layers spread out.
Here within the cord are the ductus deferens, and the testicular blood vessels. The veins that drain the testis are arranged around the artery in a plexus called the pampiniform plexus.
The testicular artery is out of sight here. The ductus deferens is a thick-walled tube. Its wall is made of smooth muscle. In this spermatic cord, we've divided the ductus deferens. The lumen is quite small.
Passing upwards in the spermatic cord, the ductus deferens reaches the inguinal canal, which is shown in Tape 3 of this atlas. Here, we're at the external inguinal ring. We'll divide these external oblique fibers, to get to the region of the internal inguinal ring, which is here.
As it passes through the internal ring, the ductus deferens passes backwards. To follow the ductus deferens, we'll divide the abdominal wall, and go round to the inside. The abdominal viscera have been removed.
The internal inguinal ring is down here. To see it better we'll remove the peritoneum, and we'll also remove some of the underlying fat. Here are the testicular vessels, passing downwards and forwards towards the internal inguinal ring.
Here's the ductus deferens. It runs backwards alongside the dome of the bladder, which is here, then crosses the ureter, which is lateral to it, and passes down behind the base of the bladder.
Here we're looking from behind at the base of the bladder, and the prostate. Part of the prostate has been removed, here. On each side the ductus deferens widens out to form the ampulla, where spermatozoa are stored. Lateral to the ampulla on each side is the seminal vesicle. The seminal vesicles produce a nutrient liquid that forms much of the total volume of the seminal fluid.
The walls of the ampulla and of the seminal vesicle are formed largely of smooth muscle. When this contracts the contents of both chambers pass together into the ejaculatory duct.
To see where the two ejaculatory ducts emerge, we'll look from in front, at a specimen that's been opened up. Here's the mucosa of the base of the bladder, here's the internal urethral meatus, here's the prostate, which we've divided coronally along with the urethra. The cut edges of the urethra are here. The ejaculatory ducts open into the urethra here, on either side of this mid-line projection, the colliculus.