Terminal spined eggs are seen in:
**Core Concept**
Terminal spined eggs are a characteristic feature of a specific parasitic infection. The eggs of this parasite have a distinctive terminal spine, which is a crucial diagnostic feature. This parasite is commonly found in humans, particularly in areas with poor sanitation.
**Why the Correct Answer is Right**
The correct answer is related to the egg morphology of the parasite *Taenia saginata*, also known as the beef tapeworm. The eggs of *T. saginata* have a terminal spine, which is a key identifying feature. When ingested, the eggs hatch in the small intestine, releasing oncospheres that penetrate the intestinal wall and migrate to the muscles, where they develop into cysticerci. The terminal spine is a distinctive feature that helps differentiate *T. saginata* eggs from those of other tapeworms.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the eggs of *T. saginata* have a terminal spine, whereas the eggs of *Taenia solium*, the pork tapeworm, do not have a spine.
* **Option B:** This option is incorrect because the eggs of *Hymenolepis nana*, the dwarf tapeworm, have a small, terminal hook, but not a spine.
* **Option C:** This option is incorrect because the eggs of *Diphyllobothrium latum*, the fish tapeworm, have a lateral spine, not a terminal one.
**Clinical Pearl / High-Yield Fact**
The terminal spine of *T. saginata* eggs is a key diagnostic feature that helps differentiate this parasite from others that can cause similar infections. Remember that the eggs of *T. saginata* have a distinctive terminal spine, which is a crucial identifying feature.
**Correct Answer:** D.