BMP activity is sufficient to promote the PhR fate. (A-C) Confocal sections of control, Tg(hsp70:bmp2b) transgenic and Tg(hs:Gal4);Tg(UAS:caBmpr1a) double transgenic embryos at 48 hours. Pineal glands are double-stained for Tg(HuC:GFP) (in green) and FRet43 (in red). Anterior is upwards. Scale bar: 16 μm. (D-I) Average numbers of Isl1+ neurons, Tg(AANAT2:GFP)+, lhx3+, FRet43+, HuC/D+ and Isl1+/Pax6+ cells in the pineal gland of control and transgenic Tg(hsp70:bmp2b) embryos heat-shocked at various stages and analyzed at 48 hours. In E and G, Tg(hs:bmp2b) embryos heat-shocked at 21 hours show a relatively mild but statistically significant effect (P=0.03 and P=0.037, respectively). (J-M) Average numbers of Isl1+ neurons, Tg(AANAT2:GFP)+, Fret43+ and HuC/D+ cells in the pineal gland of control and Tg(hs:Gal4); Tg(UAS:caBmpr1a) double-transgenic embryos at 48 hours. Heat shocks were performed at 16 hours. Error bars represent s.d. *P<0.05, **P<0.001, ***P<0.0005 using a t-test.