The invariant veil extension on contact with Schwann cells is not a function of contact-induced changes in growth cone area, growth cone speed, or filopodial number
| 5 min before contact: mean ± SD median, range | 5 min after contact: mean ± SD median, range | 10 min after contact: mean ± SD median, range | |
|---|---|---|---|
| Growth cone area, μm2 | 6.75 ± 2.41 | 8.23 ± 3.10 | 8.47 ± 1.56* |
| 7.2, 2.1–11.1 | 8.8, 2.6–13.1 | 8.7, 5.5–11.9 | |
| Growth cone speed, μm/min | 0.92 ± 1.22 | 1.23 ± 0.77 | 1.20 ± 1.70 |
| 0.5, −0.23–4.30 | 1.0, 0.12–2.47 | 1.3, −0.20–4.50 | |
| Number of filopodia per growth cone | 11.06 ± 5.84 | 10.28 ± 4.5 | 11.14 ± 4.4 |
| 8, 4–23 | 9, 3–17 | 11, 2–15 |
These data represent analysis of growth cones that made only one to four stable contacts with Schwann cells during the first 10 min after initial stable contact, to minimize the additive effects of multiple contacts (Fig. 6A, Table 3). Stable contacts do not significantly alter speed or filopodial number; they do alter area, but gradually, so that a significant difference is seen only after 10 min of contact. Of more interest, the range within each category is large, and it overlaps extensively at each time point, showing that area, speed, and filopodial number fail to account for the invariant veil extension on every filopodium that contacts a Schwann cell.n = 18, significance tested using Student's unpairedt test; asterisk shows a difference between 5 min precontact and 10 min postcontact at p < 0.03.