In tis article we will discuss about the male and female reproductive organs of roundworm.
Male Reproductive Organs:
The male reproductive organs are unpaired, monodelphic and lie in the posterior half of the body. The testis is a long and single thread like structure occupying the anterior part of pseudocoel. Presence of a single testis produces a condition known as Monorchic (Fig. 11.2).
Male Ascaris:
i. Male is smaller
ii. The posterior aperture is cloacal aperture into which digestive and genital tubes open. A pair of curved chitinoid rods or copulatory spicules or pineal spicules protrude beyond the cloacal aperture.
iii. Many ventral anal papillae are present.
iv. The tail-end is curved ventrally in the form of a hook with a conical tip.
v. No vulval aperture in the mid-ventral line, one third from the anterior end.
Female Ascaris:
i. Female is larger than male.
ii. The posterior aperture is the anal aperture where the duct of alimentary canal opens here.
iii. Only one pair of caudal papillae are present on the ventral surface.
iv. The tail-end is straight.
v. The vulval or genital aperture is situated at about 1/3 from the anterior side, on the mid- ventral line.
The distal part of the testis continues into a short and thick twisted tube, the vas deferens. It is distinguished from testis in having a lumen in place of central cytoplasmic rachis. The vas deferens joins a much thicker, wider and somewhat muscular straight tube, the seminal vesicle. It lies in the posterior third of pseudocoel below intestine. The demarcations between these three parts are very poor.
The seminal vesicle continues as the ejaculatory duct and joins the rectum to form the cloaca. On the dorsal wall of cloaca is a small invagination or pocket called the penial sac. The cloacal opening is associated with a pair of curved chitinoid spicules called penial setae, each of which is provided with a muscular penial sac. The spicules are cuticular structures which serve to open the female genital pore during copulation and help in the transference of sperms.
Female Reproductive Organs:
The female reproductive organs are double or didelphic and occupy the posterior 2/3 of the pseudocoel.
The ovaries are two in number and each ovary is a long thread like, much twisted and blind tubule. From the distal end of each ovary arises a slightly wider and tubular oviduct. Each oviduct continues into a much wider, thicker and almost untwisted tubular structure, the uterus. The uterus serves to collect fertilized eggs enclosed in shells.
The two uteri unite and form a muscular vagina which finally opens to the outside by the female gonopore or vulva situated on the ventral surface at about 1/3 of the body length from the anterior end.