Features of the structure of the reproductive system of roundworms.

The male reproductive organs are unpaired, monodelphic and lie in the back half of the body. The testis is a long and single-flow structure that occupies the anterior part of the pseudoslit. The posterior foramen is the cloacular foramen into which the digestive and genital tubes open. A pair of curved chitinoid rods or copulative spicules or pineal spicules project beyond the cloacal aperture. The posterior opening in females is the anus, in which the alimentary canal opens. Only one pair of caudal papillae is present on the ventral surface.