Target fibres are characteristically seen in a muscle biopsy of –
**Core Concept**
The **target fibre** is a pathological finding in muscle biopsy, indicative of muscle regeneration and reinervation. It is characterized by a central zone of disorganized myofibrils surrounded by a normal or hypertrophic region. This finding is associated with various neuromuscular disorders.
**Why the Correct Answer is Right**
Target fibres are typically seen in conditions where there is **denervation** and subsequent **reinnervation** of muscle fibres, such as in **spinal muscular atrophy** or **peripheral neuropathy**. The process of reinnervation leads to the formation of these characteristic target-like structures within the muscle fibres.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specifically relate to the characteristic presentation of target fibres.
**Option B:** Similarly, this option does not accurately describe the conditions under which target fibres are seen.
**Option C:** This option is also incorrect as it does not directly correlate with the pathological findings of target fibres.
**Clinical Pearl / High-Yield Fact**
Target fibres are a key diagnostic feature in the assessment of neuromuscular diseases, particularly those involving denervation and reinnervation. Recognizing these structures in a muscle biopsy is crucial for the diagnosis of conditions like **amyotrophic lateral sclerosis**.
**Correct Answer:** D. Denervating diseases