Table 2 Parameters for the cell model.

Default [VEGF]₀

0.20 ng/ml, uniform in grid space unless a VEGF gradient is specified

Vessel size

Diameter = 3–14 μm

Initial vessel length

400 μm (13–2000 μm references)

Initial cell size in vessel

Diameter: 4 μm (3–14 μm)

Length: 100 μm (20–107 μm)

Initial tip cell length

5 μm

Initial radius of tip cell

1 μm

Initial length of stalk cells

0 μm

Initial radius of formed stalk cells

2 μm

Average distance between initial capillaries

20 μm (20–40 μm)

In brain tissue: [93]

Initial ratio of stalk cell radius to stalk cell length

0.05–0.1

Number of initial endothelial cells per capillary

4 cells (2–6) cells

Number of activated cells adjacent to tip cell

1–2 cells

Initial branch length

0–4.2 μm (minimum non-zero branch length of 1.4 μm growth in one time-step of 2 hrs)

Branch angle

0–120°

Maximum elongation of stalk cells

ε_max = 0.5; maximum elongation length is 1.5 ℓ_stalk (physiologically, different stimuli cause an increase of 0.2–1.8× average length)

Maximum elongation of tip cells

ε_max = 0.5; maximum elongation length is 1.5 ℓ_tip

Maximum velocity for a cell in three-dimensions

7.5 μm/hr

Radius of lumen (r_lumen)

Constant; range 1–4 μm

Volume of stalks cells

$\text{V}=\pi \cdot ({\text{R}}^2)\cdot {{\ell }_{\text{stalk}}}^{\mu {\text{m}}^3}$

Volume of tip cells

$\text{V}=\pi \cdot ({\text{R}}^2)\cdot {{\ell }_{\text{tip}}}^{\mu {\text{m}}^3}$

Volume of stalk cells in capillary

$\text{V}=\pi \cdot ({\text{R}}_{\text{cap}}^{\text{2}}-{\text{r}}_{\text{lumen}}^2)\cdot {{\ell }_{\text{stalk}}}^{\mu {\text{m}}^3}$

Cell length change as a function of volume change, where radius to length ratio is held constant

ℓ³ ≈ volume