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Fig. 5. Most neuronal precursor cells express XlHbox 6 in stage 24 spinal cord. Dorsal is uppermost in all panels.
(A) Section at high power magnification immunostained with anti-XlHbox 6 antibodies. (B) Same section counterstained
with Hoechst 33258 viewed under dark field illumination. Note that nearly all nuclei appear to be darkly stained in panel A
and that the Hoechst fluorescence in these nuclei is quenched by the immunostaining reaction product. (C) XlHbox 6
expression in lateral plate mesoderm. Transverse section of stage 25-26 tadpole decorated with XlHbox 6 antibodies and
overstained to show more clearly the less intense staining in the lateral plate mesoderm nuclei. Abbreviations:
ecto, ectoderm; ec, ependymal canal; sc, spinal cord; myo, myotome; LPM, lateral plate mesoderm; endo, endoderm;
arch, archenteron; no, notochord, remains of blastopore. |
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Fig. 4. Expression of XlHbox 6 antigens is limited to
posterior central nervous system. (A) A tailbud embryo
(stage 25) was paraffin sectioned and immunostained for
XlHbox 6 antigens. Black areas in the spinal cord represent
immunostaining. This embryo was curled so that an anterior
section through the brain is at left and a section through the
spinal cord is at right. (B) Expression of XlHbox 6 in a
stage 38 spinal cord. This is a slightly skewed, or oblique,
lateral section. The periodic row of black dots (arrowheads)
represents staining in a very few nuclei at the ependymal
surface of the spinal cord. Abbreviations: ec, ependymal
canal; sc, spinal cord; myo, myotomes; hb, hindbrain;
no, notochord; endo, endoderm; LPM, lateral plate
mesoderm; df, dorsal fin. |
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Fig. 6. Distribution of XlHbox 6 antigens in the spinal cord
of stage 27 tadpole. A transverse section was (A)
immunostained with XlHbox 6 antibodies and (B)
counterstained with Hoechst 33258. At this stage of
development, the spinal cord starts to display a degree of
differentiation into defined layers. Now, not all of the spinal
cord nuclei express XlHbox 6 antigens. The more
peripheral nuclei which probably correspond to
differentiated primary neurons are no longer stained.
Immunostaining is confined to the entire inner layer
(ependymal layer) and a few cells that have migrated
laterally away from this mitotic zone. Note the nuclei that
are much less intensely immunostained in the lateral plate
mesoderm indicated by arrowheads. Abbreviations:
ec, ependymal canal; sc, spinal cord; no, notochord;
endo, endoderm; myo, myotome; ecto, ectoderm;
LPM, lateral plate mesoderm. |
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Fig. 7. Expression of XlHbox 6 antigens at early
metamorphosis. A stage 49 albino tadpole was
immunostained in whole-mount with anti-XlHbox 6
antibodies and then dissected under clearing solution to
remove the central nervous system and tightly associated
structures. (A) Low power magnification showing two
condensations of intensely stained nuclei in the spinal cord
(CE and LE). The arrow labelled Ant.B shows that the
same anterior border of XlHbox 6 expression (Ant.B.) is
observed as in earlier stages. (B) Dorsal view at higher
power showing the cervical and lumbar condensations in
more detail. Note the sympathetic ganglia which represent a
possible additional site of XlHbox 6 expression. (C) Lateral
view of the same tissue. Note that there are many
immunostained nuclei between CE and LE, and also
posteriorly of LE (arrowheads). Abbreviations;
Ant.B., anterior boundary of XlHbox 6 expression;
hb, hindbrain; sc, spinal cord; myo, myotome;
sg, sympathetic ganglia; no, notochord; CE, cervical
enlargement; LE, lumbar enlargement. |
