In prokaryotic cytology, which of the following is a true example of a cytoplasmic inclusion (storage/accumulation body)?

Introduction / Context:
Bacterial cells often store nutrients or by-products in discrete, non-membrane-bound granules called cytoplasmic inclusions. Examples include lipid (poly-β-hydroxybutyrate) granules, glycogen, sulfur granules, and metachromatic (volutin) granules. This question distinguishes true inclusions from other intracellular structures or artifacts.

Given Data / Assumptions:

• Cytoplasmic inclusions serve as storage depots or buoyancy structures (e.g., gas vesicles).
• Ribosomes are protein-synthesizing particles, not storage inclusions.
• Mesosomes are now regarded as artifacts of chemical fixation, not bona fide organelles or inclusions.

Concept / Approach:
Identify which listed item matches the definition of a storage/accumulation body in prokaryotes. Lipid bodies (fat globules, including PHB granules) satisfy the definition. Ribosomes are functional ribonucleoprotein complexes, and mesosomes are not accepted as real structures in living cells.

Step-by-Step Solution:

Verification / Alternative check:
Standard microbiology texts list PHB and triacylglycerol granules as lipid inclusions visible by electron microscopy and staining techniques such as Sudan Black.

Why Other Options Are Wrong:
Ribosomes: Functional translation machinery, not storage. Mesosomes: Considered artifacts formed during fixation that produce membrane infoldings; not accepted as true inclusions. All of these: Incorrect because at least two listed items are not inclusions.

Common Pitfalls:
Assuming any cytoplasmic particle is an inclusion; inclusions specifically store materials or provide buoyancy, not catalyze protein synthesis.

Final Answer:
fat globules