Pulp
Zones
| Pulpal Zone (Outermost to Innermost) | Key Components & Histological Features | High-Yield MCQ Points & "Triggers" |
| Odontoblastic Layer | * Odontoblasts (cell bodies) * Capillaries and nerve fibers running between cells | * Outermost layer of the pulp, located directly adjacent to predentin. * Formed by a single layer of cells (columnar in the crown, cuboidal/flat in the root). |
| Zone of Weil (Cell-Free Zone) | * Plexus of Rashkow (unmyelinated nerve network) * Extensive capillary plexus | * The biggest MCQ paradox: It is called "cell-free" but contains highly active non-cellular networks (nerves and blood vessels). * May temporarily disappear or shrink during active dentin formation. |
| Cell-Rich Zone | * High density of fibroblasts * Undifferentiated mesenchymal cells (UMCs) * Macrophage/Defense cells | * Contains fibroblasts (the most abundant cell type in the entire pulp). * Acts as a reservoir; UMCs here can differentiate into new odontoblasts if the primary ones are damaged. |
| Pulp Core (Central Zone) | * Main trunk lines: Large blood vessels, lymphatics, and myelinated nerve bundles | * The innermost core of the pulp tissue. * Histologically identical to the Cell-Rich zone, but distinguished by the large size of its vessels and nerve trunks rather than branching capillaries/plexuses. |