Pre and post anal papillae of Ascaris help in copulation.

Introduction:
Ascaris is a parasitic worm that infects the small intestine of humans and animals. It reproduces sexually, and copulation is an essential step in its reproductive process.

Pre-anal papillae:
- Ascaris worms have three pairs of pre-anal papillae, which are located near the posterior end of the male worm.
- These papillae are sensory structures that help in sensing the presence of a female worm for copulation.
- The male worm uses these sensory structures to locate and attach to the female worm during copulation.

Post-anal papillae:
- Ascaris worms also have three pairs of post-anal papillae, located near the posterior end of the female worm.
- These papillae play a crucial role in copulation.
- During copulation, the male worm uses its post-anal papillae to grasp and hold onto the female worm's post-anal papillae, forming a copulatory couple.
- The male's papillae fit into a groove between the female's papillae, creating a secure connection between the two worms.
- This ensures that the male's sperm is transferred directly into the female's reproductive tract for fertilization.

Significance of copulation:
- Copulation is necessary for the sexual reproduction of Ascaris.
- During copulation, the male worm transfers sperm into the female worm's reproductive tract.
- The sperm then fertilizes the eggs produced by the female worm.
- Fertilized eggs are eventually passed out of the host's body through feces and develop into infectious larvae, completing the life cycle of Ascaris.

Conclusion:
The pre and post-anal papillae of Ascaris play a crucial role in copulation, enabling the male and female worms to form a copulatory couple and facilitating the transfer of sperm for fertilization.