Fig. 2

Whole-mount in situ hybridization of zebrafish embryos using antisense bty transcripts. Wild-type zebrafish embryos were collected at intervals and stained for bty expression as described in Materials and methods. (A) 256 cell, [2.5 h post fertilization (hpf)], arrow indicates staining in the yolk syncitial layer; (B) sphere (4 hpf); (C) 30% epiboly (4.7 hpf), arrow shows prominent bty staining along the animal pole to ventral axis; (D) 75% epiboly (8 hpf); (E) 90% epiboly (9 hpf); (F) 3-somite (11 hpf); (G) 6-somite (12 hpf), arrow denotes staining in the tail bud; (H) 20 somite (18.5 hpf); (I) 30-somite (24 hpf); (J) long pec (48 hpf), the white arrow points to the pronephric tubule (traced by the dotted line) in the foreground and the black arrow points to the second, bilaterally symmetric tubule on the opposite side of the embryo; (K) 16-somite (17 hpf), the paired arrows indicate the bilateral stripes of the ICM; and (L) 16-somite (17 h) embryo stained for gata1 expression, arrows as in panel (K). Embryos in panels (A–E) are oriented with their animal poles at the top. Somite- and long pec-stage embryos (F–J) are oriented with their anterior structures to the left. The short dashed lines in panels (C–E) indicate the position of the blastoderm edge as it migrates over the yolk cell during epiboly. The long-dashed line in panel (H) and the bracket in (I) show the approximate boundaries of the hematopoietic intermediate cell mass (ICM). Embryos in panels (A–J) were micrographed in 70% glycerol/PBS using a Nikon dissecting microscope. Embryos in panels (K) and (L) were micrographed in 2:1 benzylbenzoate:benzyl alcohol using a Nikon Eclipse 800 and DIC optics.