Male reproductive organs

During early embryonic development the testes are located behind the peritoneum, just posterior to the kidneys. During the later part of fetal life they migrate, or descend, along the posterior abdominal wall, through the muscles of the ventral abdominal wall, and into an external pouch, the scrotum. The opening through which the testes pass in the abdominal wall is called the inguinal canal, which is visible in the next image (this image shows the tissues of the midventral body wall reflected). As the testes migrate, they carry with them their ducts and blood vessels; these collectively form the spermatic cord.

At the end of the testis, locate the band-like epididymis. Here, the testes have been reflected back, but in life the head of the epididymous is located cranially. The epididymis stores the sperm produced by the testes until it is released during ejaculation. The epididymis leads into the spermatic duct, or ductus deferens. The ductus deferens and the testicular artery and vein collectively form the spermatic cord. Follow the ductus deferens through the inguinal canal into the abdominal cavity, where it loops around the ureter and enters the urethra.

In this next image, locate the penis in the midventral body wall. The penis extends posteriorly from the preputial orifice, which you identified in the external anatomy section of the preceding lab.

In the next image, locate the point where the ductus deferens enter the urethra. In the next image, one of the small pair of glands, the seminal vesicles, that lie on the dorsal surface of the urethra is lifted to reveal another gland, the prostate. Another pair of glands, the bulbourethral glands, lie on either side of the urethra near the anus, but are not visible in this image. (One of the bulbourethral glands is visible and labeled in the image of the penis. It lies adjacent to the penis near the caudal end). All of these glands secrete seminal fluid, which transports the sperm at the time of ejaculation. Just distal to the bulbourethral glands the urethra enters the penis, which extends anteriorly beneath the skin. There is some muscular tissue surrounding the base of the penis; contraction of these muscles aids in expelling urine and sperm.