Emergent scar formation driven by collagen deposition from the fibroblast cascade.
Scar formation is a natural outcome of wound healing where collagen-rich repair tissue replaces the original tissue architecture. In this model, scar is not stamped unconditionally onto healed tissue but instead emerges from the local collagen concentration at the time a keratinocyte dissolves back into the continuum. Wound areas that heal before significant collagen accumulates (such as the wound margin) re-epithelialize normally, while the wound center, where myofibroblast activity was highest, develops scar. This makes scar location and density entirely dependent on the upstream fibroblast/collagen cascade.
Two scar mechanisms operate depending on configuration:
Collagen-driven scar (with fibroblasts enabled): When a cornified keratinocyte dissolves via WriteScarValue, it checks the local collagen concentration. If collagen exceeds collagen_threshold, the voxel becomes scar tissue (stratum value + 5); otherwise it becomes normal healthy stratum. Scar magnitude in the Scar PDE field mirrors collagen density directly.
Inflammation-integral scar (fallback without fibroblasts): A ScarAccumulationOp runs each step, accumulating scar as scar += inflammation * accumulation_rate. This models the clinical observation that prolonged inflammation leads to worse scarring (Ogawa 2017).
The proportional scar mode (scar_proportional_enabled) activates the ScarAccumulationOp for continuous scar field updates each step.
From modules/scar/config.toml:
| Parameter | Default | Units | Description | Source |
|---|---|---|---|---|
enabled |
true | bool | Dissolved agents stamp scar into Stratum field | Convention |
proportional_enabled |
true | bool | Cumulative scar via collagen or inflammation | Ogawa 2017 (DOI) |
accumulation_rate |
0.001 | per step | Scar from inflammation (fallback) | Calibrated |
collagen_threshold |
0.003 | a.u. | Collagen above this produces scar | Calibrated |
| Field | Source module | How used |
|---|---|---|
| Collagen | fibroblast | Scar threshold check at dissolution |
| Inflammation | inflammation | Fallback accumulation when fibroblasts disabled |
| Field | Consumer modules | What is written |
|---|---|---|
| Scar | (visualization) | Scar magnitude per voxel |
| Stratum | tissue | Scar values (stratum + 5) at keratinocyte dissolution |
| Dataset | Observable | Sources | Notes |
|---|---|---|---|
scar_formation_parameters |
Scar severity and distribution | Ogawa 2017, Gauglitz 2011 | Scar correlates with inflammation integral |
scar_remodeling |
Collagen remodeling dynamics | Xue 2015, Bailey 1998 | Long-term scar maturation |
| Column | Units | Description |
|---|---|---|
scar_magnitude |
a.u. | Mean scar field in wound cylinder |
| File | Purpose |
|---|---|
scar_pde.h |
Scar accumulation PDE field |
scar_op.h |
ScarAccumulationOp for per-step scar updates |
config.toml |
Module configuration |