cyp2aa9 is required for the HSCs formation.
(a-f) In the cyp2aa9 morphants, the expression of the definitive HSC precursors marker runx1 became decreased in the ventral floor of the dorsal aorta from 25 hpf to 36 hpf. (g,h) The number of cmyb-expressing HSCs was significantly reduced in cyp2aa9 morphants at 36 hpf. (i-l) In contrast to the control embryos at 26 hpf (i, n = 22/24) and 30 hpf (k, n = 23/24), the number of HSCs undergoing budding process from VDA (arrowheads) dramatically reduced in the cyp2aa9 morphant (j, n = 21/25; l, n = 21/25; Scale bar, 50 µm). (m) Quantifications of the number of HSCs undergoing budding process (n = 8, mean ± SD, ***p < 0.001, Student’s t-test). (n,o) In CHT (white brackets), the number of cmyb:GFP-positive cells was significantly reduced in cyp2aa9 morphants (27.6 ± 5.3, mean ± s.e.m., n = 6) comparing with the control (58.2 ± 4.1, mean ± s.e.m., n = 6). Scale bar, 100 µm. (p-s) Fluorecently labelled HSCs and DIC image showed the round-shaped HSCs (white arrowheads) were hardly detected in the CHT (white brackets) of cyp2aa9 morphants under the Tg(CD41:GFP) background (p, n = 24/24; q, n = 25/29; scale bar, 100 µm). CHT regions were zoomed in and showed in the (r,s) (scale bar, 10 µm). (t,u) The expression of T-lymphocyte marker rag1 in the thymus (arrowheads) dramatically decreased in the cyp2aa9 morphants. (a-s) Lateral views, anterior left, dorsal up. (t,u) Ventral views, anterior up.