Which feature is distinctive for Trichuris trichiura eggs?

Trichuris trichiura, commonly known as the whipworm, is notable for its distinctive eggs, which possess bipolar plugs at each end. These plugs are a key feature that helps differentiate Trichuris trichiura eggs from those of other intestinal parasites. The eggs are generally described as having a football or lemon shape and are somewhat symmetrical, with the characteristic plugs giving them an unmistakable appearance under a microscope.

The bipolar plugs are not only important for identification but also serve a functional purpose in the life cycle of the parasite. They aid in the embedding of the eggs into the intestinal mucosa, which is essential for the survival and propagation of the species.

In contrast, while factors such as shape and wall thickness are aspects one might consider when identifying other types of parasitic eggs, they do not specifically define the eggs of Trichuris trichiura. The thick walls and other potential characteristics mentioned in the other choices may apply more broadly to various types of parasitic eggs or are not uniquely identifying features for this particular species. Therefore, the most distinctive feature for Trichuris trichiura eggs is indeed the presence of the bipolar plugs.