Vas (ductus) deferens, spermatic cord, seminal vesicles

Spermatic Cord

Definition

The spermatic cord is a composite structure consisting of vessels, nerves, and ducts that connect the abdominal cavity to the testes, ensuring their vascular, neural, and reproductive functionality.

Anatomical Course

  • Formation: The spermatic cord originates at the deep inguinal ring (the entrance to the inguinal canal).
  • Pathway: It traverses the inguinal canal and emerges through the superficial inguinal ring, descending into the scrotum.
  • Termination: It attaches to the posterior border of the testes within the scrotum.

Fascial Coverings

The coverings of the spermatic cord are derived from the layers of the abdominal wall during the descent of the testes:

  1. External Spermatic Fascia: From the aponeurosis of the external oblique muscle.
  2. Cremaster Muscle and Fascia: From the internal oblique muscle and its fascia; the cremaster muscle regulates the temperature of the testes.
  3. Internal Spermatic Fascia: From the transversalis fascia.

Contents

  • Vessels:
    • Testicular artery: Branch of the abdominal aorta.
    • Artery to the ductus deferens: Branch of the inferior vesical artery.
    • Cremasteric artery and vein: Branches of the inferior epigastric artery.
    • Pampiniform venous plexus: A network of veins enveloping the testicular artery, facilitating thermoregulation by cooling the arterial blood.
  • Nerves:
    • Genital branch of the genitofemoral nerve: Supplies the cremaster muscle.
    • Autonomic nerves: Sympathetic and parasympathetic innervation for vascular control.
  • Other Structures:
    • Ductus deferens: A muscular tube conveying sperm from the epididymis to the ejaculatory duct.
    • Vestige of the processus vaginalis: A remnant of the peritoneal extension formed during testicular descent.

Ductus (Vas) Deferens

Description

The ductus deferens is a thick-walled, straight muscular tube that transports sperm from the epididymis to the ejaculatory duct, ensuring efficient sperm delivery during ejaculation.

Structure

  • Wall Composition:
    • Inner layer: Longitudinal smooth muscle.
    • Middle layer: Circular smooth muscle.
    • Outer layer: Longitudinal smooth muscle.
  • Mucosa: The lumen is lined with pseudostratified columnar epithelium featuring microvilli, which aid in the absorption and secretion processes.
  • Innervation: Autonomic innervation enables rapid contractions to propel sperm during ejaculation.

Seminal Vesicles

Anatomical Position

  • Paired, elongated glands measuring approximately 5 cm in length.
  • Located posterior to the bladder fundus, separated from the rectum by the rectovesical pouch and rectoprostatic fascia.
  • The ducts of the seminal vesicles join with the ductus deferens to form the ejaculatory ducts, which open into the prostatic urethra.

Structure

Internally, the seminal vesicles exhibit a lobulated honeycomb appearance, lined with pseudostratified columnar epithelium, specialized for secretory functions.

Function

The seminal vesicles contribute approximately 70% of the semen’s volume. Their secretions include:

  • Alkaline fluid: Neutralizes the acidic environments of the male urethra and female reproductive tract.
  • Fructose: An energy substrate for spermatozoa motility.
  • Prostaglandins: Modulate the female immune response and enhance sperm motility.
  • Clotting factors: Facilitate retention of sperm within the female reproductive system post-ejaculation.

Vasculature

  • Arterial Supply: Branches of the inferior vesical artery, internal pudendal artery, and middle rectal artery (all derived from the internal iliac artery).
  • Venous Drainage: Via veins corresponding to the arterial supply, draining into the internal iliac vein.

Innervation

  • Sympathetic: From the hypogastric plexus, crucial for secretion during ejaculation.