Fig. 1

a Expression of smad1, smad4, smad5, and smad9 in PGCs during early embryogenesis by RNA-seq^16,17. Quantification (b) of nuclear pSmad1/5/9 intensities normalized to cytoplasmic signals by pSmad1/5/9 (magenta) immunofluorescence and PGC marker Ddx4 (green) (c) in individual PGCs and somatic cells at the indicated stages and dorsal/ventral regions. PGCs were indicated by yellow arrowheads. Each dot represented one cell. Nc, number of observed cells. Error bars represented standard deviation (SD) with the mean indicated by the center line in (b). The schematics in (c) depicted the embryonic stages (animal pole view for dome stage; lateral views, dorsal to the right, for others) with PGCs shown in green. V ventral, D dorsal. d Effectiveness of BMP inhibition in embryos. Upper, experimental design for BMP inhibition using the BMP inhibitor LDN-193189; lower left panel, representative images of pSmad1/5/9 detected by immunostaining; right, bar graph showing nuclear pSmad1/5/9 intensities normalized to cytoplasmic levels in individual PGCs. Each dot represented one PGC. Nc, number of observed PGCs. Error bars represented SD with the mean indicated by the center line. e Visualization of PGCs by ddx4 ISH in DMSO- or LDN-treated embryos. The ratio of embryos with representative characteristics was indicated. f Visualization of PGCs in 3 dpf Tg(piwil1:mCherry-CAAX-nanos3 3′UTR) embryos. Upper, schematic of the transgene; lower, representative images of embryos treated with DMSO or LDN from the high stage to 1 dpf (the “Early” group). g Quantification of PGC numbers following treatment as in (f). Box plot showing PGC numbers per embryo in each group. The median is indicated by the center line. The bottom, top edges, and whiskers represent the min and max values and 1.5 times the interquartile range (IQR), respectively. Each dot represented one embryo. Ne, number of observed embryos. Statistical significance was determined by two-sided Student’s t-tests. Source data are provided as a Source Data file.