**Core Concept**
Rohr's stria, also known as Rohr's lines or granular stria, are a type of alteration in the basal ganglia seen on the microscopic examination of brain tissue, particularly in the context of neurodegenerative diseases. They are characterized by the presence of granular, eosinophilic material in the neuropil.

**Why the Correct Answer is Right**
Rohr's stria are associated with the degeneration of the basal ganglia, specifically the putamen and caudate nucleus. They are thought to represent the remnants of degenerated neurons and glial cells. The presence of Rohr's stria is often seen in conditions such as Huntington's disease, where there is significant neuronal loss in the basal ganglia. The exact mechanism of their formation is not well understood, but it is believed to be related to the breakdown of the blood-brain barrier and the subsequent accumulation of toxic substances in the brain.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Rohr's stria are not typically associated with the cerebral cortex.
**Option B:** This option is incorrect because Rohr's stria are not a feature of normal brain tissue.
**Option C:** This option is incorrect because Rohr's stria are not a type of vascular structure.

**Clinical Pearl / High-Yield Fact**
Rohr's stria are a key histopathological feature of Huntington's disease, a neurodegenerative disorder characterized by progressive chorea, psychiatric symptoms, and cognitive decline. The presence of Rohr's stria in brain tissue is a critical diagnostic clue for this condition.

**Correct Answer: D. Basal ganglia.**