Question

Hexacanth larva of Taenia solium transforms into

A) Bladder worm

B) Hydatid cyst

C) Cercaria

D) Miracidium

Answer 1

Hint: Taenia solium has a long and difficult life history. It takes two hosts to finish. Man is the primary host, and pig is the secondary host. Taenia has no free larval stage in its life cycle.

Complete Answer:

Hexacanth larvae of Taenia solium enter the intestine and thereafter use their hooks to connect to the mucous layer of the intestine. Further it uses the chemicals which are generated by the penetration glands in order to penetrate through the intestinal wall. Hexacanth larvae later reach the hepatic portal vein, which leads to the liver. Finally, the hexacanth larva transforms into a cysticercus larva, and now it relies on the nutrients following which it collects its nutrition from the tissues. This causes it to swell and grow in size. 

Further, Due to the dissolution of mesenchyme, a hollow emerges in the center of the cell mass, which is being filled with a liquid fluid. In the host blood, there is a lot of plasma in this liquid. The embryo's wall thickens on one side and invades its cavity in the shape of a knob. The knob has four suckers, a tiny rostellum, and hooks at its base on the inside. A proscolex is a type of inverted scolex. The full cysticercus, or bladder worm, is now the embryo.

The correct answer is (A).  Hexacanth larva of Tenia solium transforms into bladder worm.

Additional information:

Hydatid cyst- It is the cyst stage of Echinococcus.

Cercaris- It is a free swimming larval stage of parasitic liver fluke.

Miracidium- It is a ciliated non-swimming larva of parasitic liver fluke.

Note: Taeniasis is an infection in the bladder by adult Taenia solium. It causes very mild or no symptoms. If untreated, the infection can last for 2-3 years till the Taenia dies.