Cellular cementum is derived from:
**Core Concept**
Cellular cementum is a specialized dental tissue that covers the root of a tooth, playing a crucial role in tooth anchorage and sensory perception. It is a unique, avascular tissue composed of cementocytes embedded in a matrix of cementum.
**Why the Correct Answer is Right**
The correct answer is **C. Inner cell layer of the dental follicle**. Cellular cementum is produced by the inner cell layer of the dental follicle, which is a layer of cells surrounding the developing tooth bud. This process is known as periosteal cementogenesis. The cementocytes in cellular cementum are similar to osteocytes in bone, and they are responsible for the mineralization and turnover of the cementum matrix.
**Why Each Wrong Option is Incorrect**
**Option A:** is incorrect because the periodontal ligament, not the periosteum, plays a key role in tooth anchorage and support. While the periosteum does contribute to bone formation, it is not directly involved in cellular cementum production.
**Option B:** is incorrect because the odontoblast layer is responsible for dentin formation, not cementum. Odontoblasts produce dentin, a hard, calcified tissue beneath the enamel of the tooth.
**Option D:** is incorrect because the epithelial root sheath is a layer of epithelial cells that guides the formation of the root of the tooth, but it does not produce cellular cementum.
**Clinical Pearl / High-Yield Fact**
The cementum layer is thickest on the mesial and distal aspects of the root, which is why these areas are more prone to periodontal disease.
**Correct Answer: C. Inner cell layer of the dental follicle**