Order from disorder: Self-organization in mammalian hair patterning

Wang et al. 10.1073/pnas.0609712104.

Supporting Figures

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Fig. 7. Alignment of hair follicles at different locations on WT and Fz6^-/- skin at P5. (A and E) Head. (B and F) Upper back. (C and G) Mid back. (D and H) Lower back. Clarified skin samples are from agouti animals to more clearly visualize mature follicles (darkly pigmented) among the more numerous immature follicles (lightly pigmented). In all locations, shafts are more uniformly aligned than bulbs. (Scale bar: 1 mm.)

Fig. 8. Cross-sections of tail and back skin at P3 and P4. Arrowheads mark the surface of the epidermis, and the arrows indicate hairs that protrude from the skin surface. The first hairs protrude from the skin surface between P3 and P4 in both WT (A-D) and Fz6^-/- (E and F), as seen here in cross-section and as seen in flat mounts of clarified skin examined by differential interference contrast (DIC) microscopy (data not shown). (Scale bar: 100 mm.)

Fig. 9. Regular packing of hair follicles on the back of WT and Fz6^-/- at embryonic day 16. (A and B) GFP fluorescence from K17-GFP transgenic WT (A) or Fz6^-/- (B) mice. A regular array of more mature follicles, corresponding to the guard hairs, is embedded within a denser array of immature follicles. The mature follicles are well oriented in the WT sample and randomly oriented in the Fz6^-/- sample. (C and D) Inter-follicle distances calculated pair-wise for all follicles up to a distance of 400 mm. Both WT and Fz6 samples show regular packing of hair follicles with an exclusion zone of ≈50 mm around each follicle and a shell of nearest neighbors between ≈80 to ≈100 mm from each follicle. (Scale bar: 400 mm.)

Fig. 10. Hair follicle and epidermal disorganization in the developing Fz6^-/- tail. Distal is to the right in all images. (A-D) Skin samples (Upper) and corresponding scatter plots (Lower). Shafts orient posteriorly more effectively than bulbs. (E and G) At P0, triads of hair follicles in the tail (arrows) are arranged in an almost crystalline lattice; the larger central hair follicle is variably oriented in the Fz6^-/- tail. Follicles were visualized with a K17-GFP transgene. (F and H) Indirect illumination at P15 after removing the dermis and hairs to show epidermal plates in WT and irregular ridges in Fz6^-/-. Small white objects are the paired sebaceous glands associated with each follicle. Scatter plots are calibrated as in Fig. 1C. [Scale bars: 200 mm (A-D, F, and H) and 100 mm (E and G).

Fig. 11. Back skin cut at P0 and visualized at P3. (A) Follicles have reoriented within several hundred micrometers of the circular wound, including a near reversal of shaft orientations distal to the wound (the small Inset in A is shown enlarged in E). (B) Bulb and shaft orientations for all follicles in the large boxed area in A. (C and D) For each follicle in the large boxed area in A, bulb (C) and shaft (D) angles are shown separately, and their orientations are represented by the angle and color of the corresponding bar. [Scale bar: 1 mm (A) and 400 mm (E).]

Fig. 12. Back skin cut at P0 and visualized at P3. (A) Follicles have reoriented within several hundred micrometers of the circular cut. (B) Bulb and shaft orientations for all follicles in the boxed area in A. (C and D) For each follicle in the boxed area, bulb (C) and shaft (D) angles are shown separately, and their orientations are represented by the angle and color of the corresponding bar. (Scale bar: 1 mm.)

Fig. 13. PCP models beginning with a lattice of randomly oriented vectors. The development of each starting lattice (A-F) is shown after 10, 20, 50, and 100 iterations of the local consensus algorithm. Each vector orientation is represented by the angle and color of the corresponding line, as shown in Fig. 6.

Fig. 14. PCP models beginning with a lattice of randomly oriented vectors that are uniformly biased. The starting lattices (A-F) correspond to A-F in SI Fig. 13, with the modification that each vector has had its angle biased by the addition of a vector of length 0.5 directed toward the right. The development of each starting lattice is shown after 10, 20, 50, and 100 iterations of the local consensus algorithm. Each vector orientation is represented by the angle and color of the corresponding line as shown in Fig. 6.

Fig. 15. PCP models beginning with 89% randomly oriented vectors and 11% oriented vectors. The starting lattices (A-F) correspond to A-F in SI Fig. 13, with the modification that every ninth vector (in a triangular lattice in which each side equals three unit lengths of the original vector) is directed toward the right. These rightward vectors are located at the vertices of a regular triangular lattice of 3-fold greater linear dimensions. The development of each starting lattice is shown after 10, 20, 50, and 100 iterations of the local consensus algorithm. Each vector orientation is represented by the angle and color of the corresponding line as shown in Fig. 6. This starting lattice models the situation in which an early developing cohort of follicles (corresponding to the guard hairs) orients in advance of the later developing follicles, as seen in SI Fig. 9.

Fig. 16. PCP models beginning with four rows of uniformly oriented vectors adjacent to a lattice of randomly oriented vectors. The starting lattices (A-F) correspond to A-F in SI Fig. 13, with the modification that the top four rows are directed toward the right. The development of each starting lattice is shown after 10, 20, 50, and 100 iterations of the local consensus algorithm. Each vector orientation is represented by the angle and color of the corresponding line as shown in Fig. 6.

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