XB-IMG-82116
Xenbase Image ID: 82116
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Fig. 3. Spatial expression of XPax-2 transcripts during early Xenopus embryogenesis. Whole mount in situ hybridizations were performed on albino embryos
using digoxigenin-labeled antisense RNA probes. Hybridization events were visualized as alkaline phosphatase chromogenic reaction products. Embryos
stained in whole mount were used for sectioning and were cut at 70 mm (L, M) and 100 mM (N). (A, B) Lateral and dorsal views of a stage 13 embryo. XPax-2
expression is seen in two wedge-shaped patches of cells in the anterior 1/3 of the neural plate. Expression is absent at the midline (arrowhead). (C) Lateral
view of a stage 19 embryo. XPax-2 expression can be detected in the regions of the future midbrain-hindbrain boundary and the optic stalk (arrowhead). (D)
Dorsal view of a stage 19 embryo. Two rectangular-shaped patches of XPax-2 expressing tissues which will contribute to the midbrain-hindbrain boundary
flank the midline (arrowhead). Note that staining of XPax-2 can now also be detected in single neurons arranged in stripes on either side of the midline. (E)
Lateral view of a stage 21 embryo. XPax-2 expression is associated with the region of the future optic stalk (os) and vesicle, the midbrain-hindbrain boundary
(m-h), the otic vesicle (ov) and with cells in the spinal cord (sc). Note also the first appearance of staining in the pronephric anlage (pa). (F) Lateral view of a
stage 24 embryo. XPax-2 expression can now also be detected in the furrows of the visceral arches (va), and in both compartments of the developing
pronephric kidney, the pronephros (p) and the pronephric duct (pd). XPax-2 expression in the hindbrain (hb) is limited to the region posterior to the otic
vesicle. (G) Lateral view of a stage 28 embryo. The proctodaeum (pr) appears as a further tissue expressing XPax-2 transcripts. (H) Lateral view of a stage 32
embryo. Arrowheads indicate XPax-2 expression in the three nephrostomes of the pronephros. Note the appearance of the rectal diverticulum (rd) extending
in anterior direction (open arrow) towards the posterior end of the pronephric duct (filled arrow). (I) Lateral view of a stage 36 embryo. The pronephric duct
(filled arrow) and the rectal diverticulum (open arrow) are close to joining. Strong expression of XPax-2 is seen in the hindbrain and along the entire spinal
cord. (J) Lateral view of a stage 39 embryo. The pronephric duct has fused with the rectal diverticulum (filled arrow). XPax-2 expression is detected in the
entire excretory canal up to the point where fusion occurs with the cloaca (open arrow). The brown color in the eye is due to the onset of pigmentation. (K)
Close-up view of a stage 39 embryo to illustrate details of XPax-2 expression in the optic stalk (filled arrow), the posterior end of the midbrain (open arrow),
the otic vesicle (open arrowhead), and the hindbrain. Note also the extensive coiling of the pronephric tubules and the strong staining associated with the
nephrostomes (filled arrowheads). (L) Transversal section through a stage 32 embryo which is cut anterior to the midbrain-hindbrain boundary. XPax-2
expression is confined to the ventral portion of the optic cup (arrowheads) and to furrows of the visceral arch (arrows). (M) Transversal section through a
stained stage 32 embryo which is cut at the level of the hindbrain-spinal cord junction. Staining of the pronephroi (arrowheads) and of cells in the
ventrolateral neural tube (arrows) is indicated. (N) Horizontal section through the visceral arches of a stage 28 embryo. The plain of section is below the
eye. Arrowheads point to the expression in the furrows of the visceral arches. Embryos in shown in (A-K) were photographed uncleared, with the anterior
ends of the embryo oriented to the left. Image published in: Heller N and Brändli AW (1997) Copyright © 1997. Image reproduced with permission of the Publisher, Elsevier B. V.
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