All tapeworms except Dioecoestus (A genus allied to Taenia) are hermaphrodite. Each mature proglottid comprised of a complete set of male and female reproductive organs. These organs develop from the mesenchyme and lie embedded in it. Tapeworms show protandry in other worms the male reproductive organs differentiate before the female reproductive organs. Hence, while the mature zone of strobila consisting of 450 proglottids, the anterior 100-150 proglottids has only male system which the remaining posterior ones has both the female and the male reproductive system. After intense reproductive activity, the mature proglottid loses all its genital organs except the highly branched uterus which is filled with fertilized eggs. The segments which have both the female and male reproductive systems are called as gravid proglottids or ripe proglottids.
The following are the parts included in the male reproductive system,
Testes: They are numerous, small, spherical bodies scattered throughout the mesenchyme close to the dorsal surface.
Vas efferentia: From each testis a find ductule called as vas efferentia arises. Vas efferentia usually gets interconnected with similar ductules from the surrounding of the testes.
Vas deferens: It is a thick and convoluted tube extending up to the lateral margin of proglottid at right angles to it.
Cirrus: Outer end of vas deferens forms lumen of a thick, muscular copulatory organ called as the cirrus. The cirrus is enclosed in a firm cirrus sheath. The seminal vesicles are absent in tapeworm.
Genital atrium: The cirrus opens into a cup-shaped genital atrium through male genial pore. Genital atrium in turn opens to outside through a common gonopore. The genital papilla in the middle of the lateral margin of proglottid. Gonopore is provided with the sphincter to control the flow of the gonads. The common gonopores are arranged alternatively on both sides of the proglottid.
Following are the parts included in the female reproductive system,
Ovary: It is also called germarium. Ovary is a bilobed organ situated ventrally in the posterior part of proglottid. Both the lobes are connected by a transverse ovarian bridge.
Oviduct: It arises from the middle of ovarian bridge and opens into the ootype.
Ootype: It is spherical bulb-like structure situated at the junction of oviduct, uterus and vitelline duct. The seminal receptacle stores the sperms temporarily. The unicellular Mehli’s glands surround the ootype and secrete a slimy substance that lubricates the eggs in uterus.
Vagina: It is absent narrow tube. It originates from the female genital pore located behind the male genital pore in genital atrium. Vagina swells to form a sperm-storing sac.
Uterus: It is a blind sac-like structure originating from the ootype and extending towards the anterior side of the proglottid. In gravid proglottids uterus becomes large and highly branched with eggs in various developmental stages.
Vitelline gland: It is situated on the posterior margin of the proglottid and connected to the ootype. It connects with the ootype by a short vitelline duct. It consists of numerous follicles secreting yolk cells.
Well-developed male and female reproductive organs are present in the mature proglottids. Taenia exhibits protandry that is male reproductive organs mature earlier to the female reproductive organs. Numerous small and round testes are scattered in the parenchymal region of the proglottid. For each of this testis, vas efferens arises. All these vas efferentia unite with one another to form vas deferens which ends as a muscular copulatory organ called as cirrus. Cirrus opens into genital atrium which finally opens outside through gonopore.
A large bilobed ovary is present in each of the proglottid. The two lobes of the ovary are connected by an isthmus. Form this isthmus a common oviduct arises and it opens into ootype. In the posterior part of each proglottid, a compact vitelline gland is present which produces yolk cells. The vitelline gland opens into the ootype through oviduct. The oviduct is connected to the genital atrium through vaginal passage.
Uterus opens into the ootype as a blind duct. Uterus stores fertilized eggs. Special glands called as Mehli’s glands are present which open into the ootype. The secretions of these glands lubricate the passage of the eggs into the uterus.
Excretory canals and nerve cords are also present in each proglottid. Flame cells which are excretory and osmo-regulatory in function are present in the proglottids. These flame cells open into the excretory canal.
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