Fig. 3. The absence of the brain during development affects the migration of macrophages in response to infection.

a, b Drawing of (a) and image after in situ hybridization (ISH) for mmp7⁺ (b) of one st. 35 Xenopus embryo indicating the landmarks or reference points (1–6) for the body subdivision in the four independent areas for quantification (see Methods for details). Dashed-purple line square indicates the area shown in m, n inserts. Rostral is left and dorsal is up. c–l Quantification of number of mmp7⁺ cells in not-infected (NI, c–g) and infected (UTI, h–l), belonging each experimental group: Control (Ctrl, green), brainless (BR^–; red), spinal cord resection (SC^–; yellow) and Tailless (Tail^–; orange). Values for normalized number of mmp7⁺ cells are plotted per each region and group: face (c, h), tail (d, i), dorsal (e, j), and ventral (f, k) to detect distribution and migration patterns. Total (g, l) is the sum of the four regions. One-way ANOVA P value showed significance for (d) (P < 0.01) and (k) (P < 0.05). m, n High-magnification images showing detail of ventral region (purple square in (a)) with mmp7-positive cells in a Control (m) vs. Brainless (n) embryos. VBI: Ventral Blood Islands or primitive hematopoietic organ. o–r Number of mmp7-positive myeloid cells (normalized to the area) in not-infected (green) vs. infected (red) embryos belonging Ctrl (o), BR^– (p), SC^– (q), and Tail^– (r) groups. Counts were done on four independent regions of the whole animal body (plus the summation): face, tail, dorsal and ventral areas. Two-way ANOVA showed significant P values for all comparisons (P < 0.05). c–l, o–r Data represent the mean and S.D. of, at least, ten different embryos, from three different replicates, per each group and condition. Significant P values after post hoc Bonferroni test are indicated as *P < 0.05 and **P < 0.01. See also Supplementary Fig. S2.