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FIG. 5. Expression of gsc, Xbra, and Xnot in whole early gastrulae fixed at stage 10/ (A–C), in organizers explanted at stage 10- or stage
10 (D–I), and expression of gsc and Xbra in the late blastula (J). All explanted organizers are shown with posterior (animal) edge up and
anterior (vegetal) edge down. The shapes of organizers shown in side view in G–I vary due to slight variations in age; the organizer in G
was explanted at stage 100, and those in H and I at stage 10 (see Materials and Methods for details on how organizer shape varies with
time of explanation). (A) gsc is expressed in the vegetal half of the dorsal lip (arrowhead) and in deep endodermal cells at and below the
dorsal blastocoel floor; (B) Xbra is expressed throughout the marginal zone, but is excluded from cells above the dorsal lip (between
arrowhead and arrow); (C) Xnot is expressed throughout the animal hemisphere and is also excluded from cells above the dorsal lip
(between arrowhead and arrow); (D) gsc is expressed in the anterior (vegetal) half of the organizer only; (E) Xbra is expressed in the medial
region of the organizer; (F) Xnot is expressed within the posterior (animal) half of the organizer; (G) the gsc (purple, between arrowheads)
and Xnot (blue, between arrows) expressing domains share a common boundary in the center of the organizer; (H) Xbra (blue, between
arrowheads) partially overlaps gsc (pink, between arrows); (I) Xbra (purple, between arrowheads) partially overlaps Xnot (blue, between
arrows); and (J) in the late blastula, gsc (purple) and Xbra (blue) are expressed in separate yet overlapping compartments of the dorsal
marginal zone. Scale bars indicate relative magnifications. |
