|
Display additional annotations [+]
Gene |
Clone |
Species |
Stages |
Anatomy |
eya1
|
|
laevis
|
NF stage 13
to
NF stage 14
|
pre-chordal neural plate
,
trigeminal placode
,
lens placode
,
neural plate
,
lateral
,
[+]
|
six1
|
|
laevis
|
NF stage 13
to
NF stage 14
|
pre-chordal neural plate
,
neural crest
,
trigeminal placode
,
lens placode
,
neural plate
,
[+]
|
six4
|
|
laevis
|
NF stage 13
to
NF stage 14
|
pre-chordal neural plate
,
trigeminal placode
,
lens placode
,
neural plate
,
lateral
|
pax3
|
|
laevis
|
NF stage 13
to
NF stage 14
|
anterior neural fold
,
cranial neural crest
,
profundal placode
,
neural plate border
|
pax8
|
|
laevis
|
NF stage 13
to
NF stage 14
|
intermediate mesoderm
|
sox2
|
|
laevis
|
NF stage 13
to
NF stage 14
|
pre-chordal neural plate
,
trigeminal placode
,
neural plate
,
lateral
|
sox3
|
|
laevis
|
NF stage 13
to
NF stage 14
|
pre-chordal neural plate
,
chordal neural plate
,
trigeminal placode
,
neural plate
,
profundal placode
,
[+]
|
pax2
|
|
laevis
|
NF stage 13
to
NF stage 14
|
pre-chordal neural plate
|
irx1
|
|
laevis
|
NF stage 13
to
NF stage 14
|
chordal neural plate
,
trigeminal placode
,
lens placode
,
lateral
,
profundal placode
,
[+]
|
msx1
|
|
laevis
|
NF stage 13
to
NF stage 14
|
neural crest
,
trigeminal placode
,
lens placode
,
neural plate
,
profundal placode
,
[+]
|
tbx2
|
|
laevis
|
NF stage 13
to
NF stage 14
|
cement gland primordium
|
dlx3
|
|
laevis
|
NF stage 13
to
NF stage 14
|
ectoderm
,
cement gland primordium
,
trigeminal placode
,
lens placode
,
neural plate border
,
[+]
|
foxi4
|
|
laevis
|
NF stage 13
to
NF stage 14
|
trigeminal placode
,
neural plate
,
lateral
,
anterior neural fold
,
profundal placode
,
[+]
|
|
|
Fig. 1. Placodal gene expression patterns in neural plate stage Xenopus embryos (stages 13–14) in dorsal view (anterior is to the left, all embryos are equally oriented). To facilitate comparison of the placodal expression domains of different genes, color-coded arrows and arrowheads corresponding to different placodal expression domains of Pax genes are used for the identification of comparable regions of gene expression (for more detailed labeling, see Fig. 12). Colors are explained in the schematic drawing, which depicts the approximate relative position of some gene expression domains and lists the placodes to which they will give rise subsequently. Green arrowheads identify placodal gene expression immediately rostral to the anterior neural plate border (prospective adenohypophysial placode medially and prospective olfactory placodes laterally), whereas green arrows identify placodal gene expression rostrolateral to the anterior neural plate (prospective lens and trigeminal placodes). Black arrows in D indicate the border of Dlx3 expression in superficial ectoderm, which extends further medial than its border of expression in the deep ectodermal layer (colored arrows). Black arrowheads in E indicate Msx1 expression in anterior neural plate. White asterisks in E and L indicate expression of Msx1 and Pax3, respectively, in a region encompassing neural crest and lateralmost neural plate. For detailed description, see text. Abbreviations: Ad/Ol, anterior placodal area, from which adenohypophysial (Ad) and olfactory (Ol) placodes develop; anp, anterior neural plate; cg, cement gland; L, lens placode; LL/Ot/EB, posterior placodal area, from which lateral line (LL), otic (Ot), and epibranchial (EB) placodes develop; np, neural plate; PN, pronephros; Pr, profundal placode; pnp, posterior neural plate; V, trigeminal placode. |
|
Display additional annotations [+]
Gene |
Clone |
Species |
Stages |
Anatomy |
eya1
|
|
laevis
|
NF stage 13
to
NF stage 14
|
trigeminal placode
,
neural plate
,
anterior neural fold
|
six1
|
|
laevis
|
NF stage 13
to
NF stage 14
|
trigeminal placode
,
neural plate
,
anterior neural fold
|
six4
|
|
laevis
|
NF stage 13
to
NF stage 14
|
trigeminal placode
,
neural plate
,
anterior neural fold
|
pax3
|
|
laevis
|
NF stage 13
to
NF stage 14
|
neural plate
,
anterior neural fold
|
pax8
|
|
laevis
|
NF stage 13
to
NF stage 14
|
intermediate mesoderm
|
sox2
|
|
laevis
|
NF stage 13
to
NF stage 14
|
neural plate
,
anterior neural fold
|
sox3
|
|
laevis
|
NF stage 13
to
NF stage 14
|
trigeminal placode
,
neural plate
,
anterior neural fold
|
pax2
|
|
laevis
|
NF stage 13
to
NF stage 14
|
pre-chordal neural plate
|
irx1
|
|
laevis
|
NF stage 13
to
NF stage 14
|
chordal neural plate
,
trigeminal placode
,
neural plate
|
msx1
|
|
laevis
|
NF stage 13
to
NF stage 14
|
chordal neural plate
,
trigeminal placode
,
neural plate
|
tbx2
|
|
laevis
|
NF stage 13
to
NF stage 14
|
|
tbx2
|
|
laevis
|
NF stage 21
|
cement gland primordium
,
otic placode
|
dlx3
|
|
laevis
|
NF stage 13
to
NF stage 14
|
|
foxi4
|
|
laevis
|
NF stage 13
to
NF stage 14
|
trigeminal placode
|
foxi4
|
|
laevis
|
NF stage 13
to
NF stage 14
|
ectoderm
,
olfactory placode
,
neural crest
,
trigeminal placode
,
lens placode
,
[+]
|
|
|
Fig. 2. Placodal gene expression patterns in neural plate stage Xenopus embryos (stages 13–14) in lateral view (anterior is to the left, all embryos are equally oriented). As in Fig. 1, color-coded arrows and arrowheads are used for the identification of comparable regions of gene expression as indicated in the schematic drawing. Green arrowhead corresponds to the lateral green arrowhead in Fig. 1 (prospective olfactory placode). Black asterisk in D indicates region where Dlx3 is expressed only in the superficial ectodermal layer. Black arrowheads in E indicate Msx1 expression in anterior neural plate. White asterisks in E and L indicate expression of Msx1 and Pax3, respectively, in a region encompassing neural crest and lateralmost neural plate. Insert in J shows incipient placodal Tbx2 expression at a slightly later (neural fold) stage. For detailed description, see text. For abbreviations, see Fig. 1. |
|
Display additional annotations [+]
Gene |
Clone |
Species |
Stages |
Anatomy |
eya1
|
|
laevis
|
NF stage 13
to
NF stage 14
|
prechordal plate
,
anterior neural fold
|
six1
|
|
laevis
|
NF stage 13
to
NF stage 14
|
prechordal plate
,
anterior neural fold
|
sox3
|
|
laevis
|
NF stage 13
to
NF stage 14
|
neuroectoderm
,
neuroectoderm outer layer
,
neural plate
,
sensorial layer of neurectoderm
|
sox3
|
|
laevis
|
NF stage 13
to
NF stage 14
|
ectoderm
,
neural plate
,
superficial
,
deep
,
anterior
|
sox3
|
|
laevis
|
NF stage 13
|
neuroectoderm
,
neuroectoderm outer layer
,
neural plate
,
sensorial layer of neurectoderm
|
msx1
|
|
laevis
|
NF stage 13
to
NF stage 14
|
neural plate
,
anterior neural fold
|
dlx3
|
|
laevis
|
NF stage 13
to
NF stage 14
|
cement gland primordium
,
superficial
,
deep
|
|
|
Fig. 5. Positioning of gene expression domains at the anterior neural plate border as revealed by double-staining procedures in sagittal sections (anterior is to the left) of neural plate stage Xenopus embryos (stages 13–14). For each gene analyzed, a first panel depicts gene expression at the anterior neural plate border, a second panel shows the pattern of nuclear Sox3 immunostaining in the same section (apparent nonnuclear staining in the endoderm is an artifact due to autofluorescence of yolk granules), and a third panel presents a superposition of the first two panels. (A–C) Distribution of Sox3 expression (A) and Sox3 immunostaining (B). The anterior border of the neural plate is indicated by grey arrows. The superficial ectodermal layer is indicated by asterisks. Sox3 expression and immunostaining is found in the superficial (in the domain marked by a white asterisk) and deep ectodermal layers. The rostral limit of expression in the deep ectodermal layer (black arrowheads) extends beyond the neural plate border. Cells within this area of Sox3 expression rostral to the neural plate border are also immunopositive for Sox3 (black arrows). However, no Sox3-immunopositive cells are yet discernible in the lateral crescent-shaped domain of Sox3 expression (identified by blue arrowheads in A) as is particularly evident in the inserts of A–C depicting sections of the same specimen at a more lateral level. (D–R) Comparison of the expression pattern of Six1 (D–F), Eya1 (G–I), Dlx3 (J–L), Msx1 (M–O), and Pax6 (P–R) at the anterior neural plate border with Sox3 immunostaining. Inserts in D and G show Six1 and Eya1 expression patterns, respectively, in additional specimens. The borders of expression of each gene in the deep ectodermal layer are indicated by arrowheads. Double-labeled cells, which show expression of the respective gene as well as Sox3 immunostaining, are identified by black or white arrows. Because Pax6 expression and Sox3 immunoreactivity are largely coextensive, double-labeled cells are not specifically marked in P–R. Black asterisks indicate the superficial ectodermal layer (which is artifactually missing in D). White asterisks in L indicate cells in the superficial ectodermal layer that express Dlx3 and are Sox3 immunopositive (posterior border ofDlx3 expression is immediately to the right of panel). Red arrows in M–O indicate Sox3-immunopositive cells located rostral to the domain of Msx1 expression in the anteriormost neural plate. Scale bar in A: 100 μm (for all panels). |
|
Display additional annotations [+]
Gene |
Clone |
Species |
Stages |
Anatomy |
six1
|
|
laevis
|
NF stage 16
|
trigeminal placode
,
anterior neural fold
,
profundal placode
|
pax3
|
|
laevis
|
NF stage 14
|
anterior neural fold
,
profundal placode
|
pax3
|
|
laevis
|
NF stage 16
|
pre-chordal neural plate
,
chordal neural plate
,
neural plate
,
profundal placode
|
pax8
|
|
laevis
|
NF stage 14
|
profundal placode
,
posterior placodal area
|
pax8
|
|
laevis
|
NF stage 16
|
profundal placode
|
sox3
|
|
laevis
|
NF stage 14
|
pre-chordal neural plate
,
chordal neural plate
,
trigeminal placode
,
neural plate
|
sox3
|
|
laevis
|
NF stage 16
|
pre-chordal neural plate
,
chordal neural plate
,
trigeminal placode
,
neural plate
,
profundal placode
|
|
|
Fig. 7. Positioning of Pax gene expression domains relative to Sox3 as revealed by whole mount double in situ hybridization. Dorsal views (A, D, and G) of neural plate stage Xenopus embryos (stage 14; anterior to the left) and lateral (B, E, and H) and oblique dorsolateral (C, F, and I) views of neural fold stage Xenopus embryos (stage 16; anterior to the left) demonstrating the position of Pax6 (A–C), Pax3 (D–F), and Pax8 (G–I) expression domains relative to Sox3 expression. Inserts in A, D, and G show Sox3 expression individually for clarification. Asterisks indicate lateral domain of Sox3 expression. Arrows indicate anterior and posterior borders of placodal expression domains for Pax6 (green arrows: prospective lens and trigeminal placodes, A–C), Pax3 (yellow arrows: prospective profundal placode, D–F), and Pax8 (brown arrows: posterior placodal area, G–I). The green arrowhead in B and C indicates Pax6 expression in the lateral part of the anterior placodal area (prospective olfactory placode). Inserts in B, E, and H identify the corresponding subdomains of Six1 expression. |
|
Display additional annotations [+]
Gene |
Clone |
Species |
Stages |
Anatomy |
eya1
|
|
laevis
|
NF stage 21
to
NF stage 22
|
olfactory placode
,
otic placode
,
trigeminal placode
|
six1
|
|
laevis
|
NF stage 21
to
NF stage 22
|
olfactory placode
,
otic placode
,
trigeminal placode
|
six4
|
|
laevis
|
NF stage 21
to
NF stage 22
|
olfactory placode
,
otic placode
,
trigeminal placode
,
profundal placode
,
posterior placodal area
|
pax3
|
|
laevis
|
NF stage 21
to
NF stage 22
|
brain
,
forebrain
,
midbrain
,
hindbrain
,
hatching gland
,
[+]
|
pax8
|
|
laevis
|
NF stage 21
to
NF stage 22
|
otic placode
,
pronephric mesenchyme
,
posterior placodal area
|
sox2
|
|
laevis
|
NF stage 21
to
NF stage 22
|
olfactory placode
,
otic vesicle
,
lens
,
forebrain
,
midbrain
,
[+]
|
sox3
|
|
laevis
|
NF stage 21
to
NF stage 22
|
olfactory placode
,
otic vesicle
,
forebrain
,
midbrain
,
hindbrain
,
[+]
|
pax2
|
|
laevis
|
NF stage 21
to
NF stage 22
|
midbrain-hindbrain boundary
,
otic placode
,
optic vesicle
,
posterior placodal area
|
irx1
|
|
laevis
|
NF stage 21
to
NF stage 22
|
midbrain
,
otic placode
,
trigeminal placode
|
msx1
|
|
laevis
|
NF stage 21
to
NF stage 22
|
hindbrain
,
spinal cord
,
branchial arch
,
otic placode
,
ventral
|
tbx2
|
|
laevis
|
NF stage 21
to
NF stage 22
|
otic vesicle
,
cement gland primordium
,
trigeminal placode
,
lens placode
,
profundal placode
,
[+]
|
dlx3
|
|
laevis
|
NF stage 21
to
NF stage 22
|
olfactory placode
,
cement gland primordium
,
otic placode
,
trigeminal placode
|
foxi4
|
|
laevis
|
NF stage 21
to
NF stage 22
|
trigeminal placode
,
epibranchial placode
,
profundal placode
,
posterior placodal area
|
|
|
Fig. 9. Placodal gene expression patterns in early tail bud Xenopus embryos (stages 21–22) in lateral views (anterior is to the left) and right frontal views (inserts). Color-coded arrows and arrowheads are used for the identification of comparable regions of gene expression. Expression in the prospective lens placode (which is not yet thickened at this stage) is indicated by L. Colors are explained in the schematic drawing, which shows the distribution of placodes in a stage 21 embryo (modified after Schlosser and Northcutt, 2000; see Fig. 14 for detailed explanation). The unpaired adenohypophysial placode is located medial to the ventral part of the olfactory placode and is, thus, hidden behind the olfactory placode in this lateral perspective (indicated by light green arrow and Ad in brackets). Various shades of green identify placodes (including the prospective lens placode) expressing Pax6, yellow identifies the profundal placode expressing Pax3, and brown and pink jointly identify the posterior placodal area expressing Pax2 and Pax8, with pink being reserved for the subregion, which will form the otic vesicle. Blue–green asterisks indicate downregulation of the respective genes in the region of the prospective lens placode, whereas brown asterisks indicate downregulation of the respective genes in a region intervening between the anterior and posterior subregions of the posterior placodal area. The pink and brown asterisks in I indicate downregulation of FoxI1c expression in the dorsal part of the posterior placodal area. For detailed description, see text. For additional abbreviations, see Fig. 1. |
|
Display additional annotations [+]
Gene |
Clone |
Species |
Stages |
Anatomy |
eya1
|
|
laevis
|
NF stage 24
to
NF stage 27
|
olfactory placode
,
somite
,
trigeminal placode
,
epibranchial placode
,
lateral line placode
|
six1
|
|
laevis
|
NF stage 24
to
NF stage 27
|
olfactory placode
,
somite
,
otic placode
,
trigeminal placode
,
lens placode
,
[+]
|
six4
|
|
laevis
|
NF stage 24
to
NF stage 27
|
olfactory placode
,
otic placode
,
trigeminal placode
,
epibranchial placode
,
lateral line placode
|
pax3
|
|
laevis
|
NF stage 24
to
NF stage 27
|
forebrain
,
midbrain
,
hindbrain
,
hatching gland
,
profundus ganglion
|
pax8
|
|
laevis
|
NF stage 24
to
NF stage 27
|
otic vesicle
,
pronephric mesenchyme
,
epibranchial placode
,
lateral line placode
|
sox2
|
|
laevis
|
NF stage 24
to
NF stage 27
|
olfactory placode
,
forebrain
,
midbrain
,
hindbrain
,
trigeminal placode
,
[+]
|
sox3
|
|
laevis
|
NF stage 24
to
NF stage 27
|
olfactory placode
,
otic vesicle
,
forebrain
,
midbrain
,
hindbrain
,
[+]
|
pax2
|
|
laevis
|
NF stage 24
to
NF stage 27
|
otic vesicle
,
midbrain-hindbrain boundary
,
spinal cord
,
optic vesicle
,
pronephric mesenchyme
,
[+]
|
irx1
|
|
laevis
|
NF stage 24
to
NF stage 27
|
midbrain
,
hindbrain
,
otic placode
,
trigeminal placode
,
lens placode
,
[+]
|
msx1
|
|
laevis
|
NF stage 24
to
NF stage 27
|
otic vesicle
,
midbrain
,
hindbrain
,
optic vesicle
,
dorsal
,
[+]
|
tbx2
|
|
laevis
|
NF stage 24
to
NF stage 27
|
otic vesicle
,
cement gland primordium
,
trigeminal placode
,
lens placode
,
profundal placode
,
[+]
|
dlx3
|
|
laevis
|
NF stage 24
to
NF stage 27
|
olfactory placode
,
otic vesicle
,
cement gland primordium
,
trigeminal placode
,
epibranchial placode
,
[+]
|
foxi4
|
|
laevis
|
NF stage 24
to
NF stage 27
|
trigeminal placode
,
lens placode
,
epibranchial placode
,
lateral line placode
|
|
|
Fig. 10. Placodal gene expression patterns in mid-tail bud Xenopus embryos (stages 24–27) in lateral views (anterior is to the left). As in Fig. 9, color-coded arrows and arrowheads are used for the identification of comparable regions of gene expression. Expression in the lens placode is indicated by L. Colors are explained in the schematic drawings, which show the distribution of placodes in stages 24 and 27 embryos (modified after Schlosser and Northcutt, 2000; see Fig. 14 for detailed explanation). By stage 24, the posterior placodal area has extended caudally, the formation of the otic vesicle by invagination of the otic placode has begun, and epibranchial placodes (orange) begin to become recognizable in its ventral part (Schlosser and Northcutt, 2000). By stage 27, the posterior placodal area has broken up into distinct placodes, while invagination of the otic vesicle is continuing (Schlosser and Northcutt, 2000). The lens placode has appeared as a focal thickening. The orange and brown double arrows indicate expression of the respective genes in a region encompassing the facial epibranchial placode and anteroventral lateral line placode, because both placodes are closely apposed and, thus, cannot be differentiated from each other. White asterisks indicate gene expression in the pharyngeal pouches (which can be clearly distinguished from placodal expression domains in transverse sections). The brown asterisk in M indicates downregulation of Pax2 in the region of the anterodorsal lateral line placode. For detailed description, see text. Abbreviations: EB, epibranchial placodes; LL, lateral line placodes; Ot, otic placode or vesicle; vba, ventral branchial arch region (all three germ layers). For additional abbreviations, see Fig. 1. |
|
Display additional annotations [+]
Gene |
Clone |
Species |
Stages |
Anatomy |
eya1
|
|
laevis
|
NF stage 32
to
NF stage 33 and 34
|
otic vesicle
,
trigeminal placode
,
epibranchial placode
,
lateral line placode
,
profundal placode
,
[+]
|
six1
|
|
laevis
|
NF stage 32
to
NF stage 33 and 34
|
olfactory placode
,
otic placode
,
epibranchial placode
,
profundus ganglion
,
trigeminal ganglion
,
[+]
|
six4
|
|
laevis
|
NF stage 32
to
NF stage 33 and 34
|
otic vesicle
,
epibranchial placode
,
profundus ganglion
,
trigeminal ganglion
,
lateral line placode
|
pax3
|
|
laevis
|
NF stage 32
to
NF stage 33 and 34
|
hindbrain
,
hatching gland
,
pronephric sinus
,
trigeminal ganglion
|
pax8
|
|
laevis
|
NF stage 32
to
NF stage 33 and 34
|
otic vesicle
,
pronephric duct
,
epibranchial placode
,
pronephric kidney
|
sox2
|
|
laevis
|
NF stage 32
to
NF stage 33 and 34
|
olfactory placode
,
otic vesicle
,
lens
,
forebrain
,
midbrain
,
[+]
|
sox3
|
|
laevis
|
NF stage 32
to
NF stage 33 and 34
|
olfactory placode
,
otic vesicle
,
lens
,
forebrain
,
midbrain
,
[+]
|
pax2
|
|
laevis
|
NF stage 32
to
NF stage 33 and 34
|
otic vesicle
,
hindbrain
,
midbrain-hindbrain boundary
,
spinal cord
,
pronephric duct
,
[+]
|
irx1
|
|
laevis
|
NF stage 32
to
NF stage 33 and 34
|
otic vesicle
,
midbrain-hindbrain boundary
,
pharyngeal arch
,
branchial arch
,
trigeminal placode
,
[+]
|
msx1
|
|
laevis
|
NF stage 32
to
NF stage 33 and 34
|
otic vesicle
,
lens
,
branchial arch
,
lens placode
,
ventral
,
[+]
|
msx1
|
|
laevis
|
NF stage 32
to
NF stage 33 and 34
|
otic vesicle
,
hindbrain
,
branchial arch
,
ventral
|
tbx2
|
|
laevis
|
NF stage 32
to
NF stage 33 and 34
|
otic vesicle
,
lens
,
branchial arch
,
trigeminal placode
,
optic vesicle
,
[+]
|
dlx3
|
|
laevis
|
NF stage 32
to
NF stage 33 and 34
|
olfactory placode
,
otic vesicle
,
pharyngeal arch
,
epibranchial placode
|
foxi4
|
|
laevis
|
NF stage 32
to
NF stage 33 and 34
|
pharyngeal arch
,
trigeminal placode
,
epibranchial placode
,
profundus ganglion
,
trigeminal ganglion
,
[+]
|
|
|
Fig. 11. Placodal gene expression patterns in late tail bud Xenopus embryos (stages 32–34) in lateral views (anterior is to the left). As in Fig. 9, color-coded arrows and arrowheads are used for the identification of comparable regions of gene expression. Expression in the lens is indicated by L. Colors are explained in the schematic drawing, depicting the distribution of placodes in a stage 33/34 embryo (modified after Schlosser and Northcutt, 2000; see Fig. 14 for detailed explanation). By stage 33/34, the profundal placode has disappeared, the trigeminal placode is shrinking rapidly, the lens placode and otic placode have completely invaginated to form the lens and the otic vesicle, respectively, and the lateral line primordia have begun to extend from the lateral line placodes (Schlosser and Northcutt, 2000). Again, orange and brown double arrows indicate expression of the respective genes in a region encompassing facial epibranchial placode and anteroventral lateral line placode. White asterisks indicate gene expression in the pharyngeal pouches. Green and yellow asterisks indicate gene expression in the trigeminal and profundal ganglia (which are fused proximately), respectively. For detailed description, see text. Abbreviations: bam, branchial arch mesenchyme; L, lens; Ot, otic vesicle; vba, ventral branchial arch region (all three germ layers). For additional abbreviations, see Fig. 1. |