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. Author manuscript; available in PMC: 2014 Dec 12.
Published in final edited form as: Nat Commun. 2014 May 20;5:3839. doi: 10.1038/ncomms4839

Figure 3. Bmp7 specifies positional identity along the tonotopic axis of the BP.

Figure 3

(a) Maximum z-projections from the regions indicated of BP explant cultures labeled with phalloidin. BPswere maintained for 6 daysIV from E6.5 in control media or media supplemented with0.4 μg/mL Bmp7. While hair cell density is comparable between the two conditions in the distal region of the BP, a marked increase in density is present in the proximal region of the Bmp7-treated explant. (b)Higher magnification images from the sample in a. (c)Quantification of changes in hair cell density in the indicated regions in response to Bmp7-treatment.. Treatment with Bmp7 causes a significant increase in hair cell density in the proximal region of the BP. As a result, the gradient of hair cell density across the tonotopic axis is abolished.(d)Quantification of mean hair cell lumenal surface area in control and Bmp7-treated cultures in the indicated regions of the BP. Bmp7-treatment induces a significant decrease in proximal hair cells but has no effect on distal hair cells. (e)BP explants established at E6.5, maintained for 6 DIV and then labeled with anti-Calbindin. In the Bmp7-treated explant, Calbindin expression in proximal hair cells appears comparable to expression in hair cells located in the middle region in controls. Similarly, hair cells located in the middle region in Bmp7-treated explants appear to be negative for Calbindin, a phenotype that is restricted to the distal region in control BPs. (f) Quantification of the extension of the distal calbindin phenotype (hair cells negative for Calbindin) along the tonotopic axis from the distal tip in control and Bmp7-treated explants. Bmp7 causes a significant increase in the distal extension of this phenotype. (g) Quantification of mean Calbindin intensity in hair cells from proximal and distal regions of the BP in control and Bmp7-treated explants. Bmp7-treatment causes a significant decrease in Calbindin expression in proximal hair cells.Data are presented as mean ± sem. *;p < 0.02, **; p<0.01, based on Student's t-test + Bonferroni correction. Scale bars (a = 100 μm, b = 10 μm, e = 100 μm). For ccontrols n = 14 and for Bmp7-treated n = 8.