Ejaculatory duct

Definition

A duct in the male reproductive system that conveys sperm from the vas deferens (or equivalent sperm duct) toward the exterior, often receiving secretions from accessory glands along its course. In arthropods, the ejaculatory duct typically extends from the fusion point of paired vasa deferentia or from the seminal vesicle region, passing through the phallic or genital structures to terminate at the gonopore or aedeagal opening. It may be cuticularized, muscular, or associated with reversible sacs (ejaculatory sacs) that assist in sperm expulsion.

Etymology

Latin ejaculatus (thrown out, emitted), past participle of ejaculari, from e- (out) + jaculari (to throw); ductus (led, conducted)

Example

In male grasshoppers (Acrididae), the ejaculatory duct runs through the elongated aedeagus and terminates at the phallotreme, where sperm mixed with spermatophore-forming secretions from the accessory glands is deposited into the female's bursa copulatrix during copulation.

Related Terms

• vas deferens
• Aedeagus
• Gonopore
• accessory gland
• Spermatophore
• seminal vesicle
• ejaculatory sac
• phallus

Usage Notes

In insects, the ejaculatory duct is often distinguished from the vasa deferentia by its more distal position and its passage through modified abdominal segments (genital capsule) rather than the main body cavity. Some authors restrict 'ejaculatory duct' to the cuticularized portion within the phallus, while others include the upstream muscular duct. Contrast with 'sperm duct' as a broader term encompassing any channel carrying sperm. In spiders and some other arachnids, the paired ejaculatory ducts may remain separate rather than fusing into a single median duct.