| |
Fig. 3. Immunolocalization of XlHbox 8 protein. Xenopus embryos staged according to Nieuwkoop & Faber (1967) were
serially sectioned and stained with anti-XlHbox 8 antibody. (A) Frontal section of a stage 33 embryo. A narrow band of
expression of the XlHbox 8 protein (bracketed) is faintly visible in the endoderm slightly posterior to the pharynx.
(B) Sagittal section through the left half of a stage 38 embryo. In this section the anterior border where expression of the
XlHbox 8 antigen starts is clearly visible. The dorsal and ventral pancreatic rudiments are positive for the antigen as
indicated. The stained endodermal tube in the centre will later mature into duodenum (note the cavity at its anterior tip).
The liver is entirely unstained. (C) Sagittal section through a stage 41 embryo. Note the band of expression in the endoderm
(dark stain) while the remainder of the embryo is unstained. (D) Transverse section (slightly oblique angle) through a stage
41 embryo at low magnification. Only endodermal cells are stained; neuroectoderm and mesoderm are unstained. (E) Same
section as in D but at higher magnification. Note XlHbox 8 expression in the gut epithelium as well as in the pancreatic
excretory duct. All nuclei in the endodermal band are stained; the lower right corner appears unstained because of the
slightly oblique plane of sectioning. (F) The same section as in E counterstained with the fluorescent DNA stain Hoechst
33258. (G) Section through a stage 49 embryo. All nuclei in the epithelium of the duodenum and pancreatic ducts are
stained, but only a small percentage of cells within the pancreas proper contain XlHbox 8 protein at this stage. No XlHbox 8
protein is expressed in liver, stomach, or small intestine. (H) Same section shown in G at higher magnification. (I) Section
through an adult Xenopus pancreas. All the nuclei in the pancreatic duct system are stained with anti-XlHbox 8 antibody.
The nuclei of cells in the acini are weakly stained. Abbreviations; ph, pharynx; en, endoderm; p, pancreas; dp, dorsal
pancreatic anlage; vp, ventral pancreatic anlage; 1, liver; pd, pancreatic excretory duct; s, stomach; in, intestine; ens, central
nervous system; pn, pronephros. |
