Figure 6.

Roof plate induction of D1A and D1B neurons requires TGFβ-related signaling. (A) GDF7 induction of LH2A/LH2B⁺ neurons in chick [i] explants is blocked by addition of Noggin (N; 20 nm) but not by Follistatin (F; 80 nm). (B) Follistatin, but not Noggin, blocks the BMP6-mediated induction of LH2A/LH2B⁺ neurons. (C–E) Quail neural plate [i] explants [stained with anti-quail cell-specific perinuclear marker (QCPN), green] cultured alone (C) for 48 hr do not generate LH2A/LH2B⁺ neurons (red), whereas explants cultured with mouse roof plate (D) generate many LH2A/LH2B⁺ neurons. Addition of Noggin alone (20 nm) or Follistatin alone (80 nm) partially blocks the induction of LH2A/LH2B⁺ neurons by mouse roof plate (F). Addition of both Noggin and Follistatin reduces mouse roof plate-mediated induction of LH2A/LH2B⁺ neurons by ∼95% (E,F). Histograms show mean ± s.d. for 6–12 explants.