Limits...
Prepatterning and patterning of the thalamus along embryonic development of Xenopus laevis.

Bandín S, Morona R, González A - Front Neuroanat (2015)

Bottom Line: The largely conserved expressions of Nkx2.2 in the rostral thalamic domain vs.Gbx2 and Ngn2 (among others) in the caudal domain strongly suggest the role of Shh as morphogen in the amphibian thalamus.All these data showed that the molecular characteristics observed during preparttening and patterning in the thalamus of the anuran Xenopus (anamniote) share many features with those described during thalamic development in amniotes (common patterns in tetrapods) but also with zebrafish, strengthening the idea of a basic organization of this diencephalic region across vertebrates.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Biology, Department of Cell Biology, University Complutense Madrid, Spain.

ABSTRACT
Previous developmental studies of the thalamus (alar part of the diencephalic prosomere p2) have defined the molecular basis for the acquisition of the thalamic competence (preparttening), the subsequent formation of the secondary organizer in the zona limitans intrathalamica, and the early specification of two anteroposterior domains (rostral and caudal progenitor domains) in response to inducing activities and that are shared in birds and mammals. In the present study we have analyzed the embryonic development of the thalamus in the anuran Xenopus laevis to determine conserved or specific features in the amphibian diencephalon. From early embryonic stages to the beginning of the larval period, the expression patterns of 22 markers were analyzed by means of combined In situ hybridization (ISH) and immunohistochemical techniques. The early genoarchitecture observed in the diencephalon allowed us to discern the boundaries of the thalamus with the prethalamus, pretectum, and epithalamus. Common molecular features were observed in the thalamic prepatterning among vertebrates in which Wnt3a, Fez, Pax6 and Xiro1 expression were of particular importance in Xenopus. The formation of the zona limitans intrathalamica was observed, as in other vertebrates, by the progressive expression of Shh. The largely conserved expressions of Nkx2.2 in the rostral thalamic domain vs. Gbx2 and Ngn2 (among others) in the caudal domain strongly suggest the role of Shh as morphogen in the amphibian thalamus. All these data showed that the molecular characteristics observed during preparttening and patterning in the thalamus of the anuran Xenopus (anamniote) share many features with those described during thalamic development in amniotes (common patterns in tetrapods) but also with zebrafish, strengthening the idea of a basic organization of this diencephalic region across vertebrates.

No MeSH data available.


Related in: MedlinePlus

Expression of thalamic markers at embryonic stages 40/41. Microphotographs of transverse (A–E,G–I,K–M) or sagittal (F,J,N,O) sections of embryos at stages 40/41. In all cases, photographs correspond to combination of ISH (purple) with IHC (brown), except for a double fluorescent ISH (red) and IHC (green) panel (E) and two single ISH (purple; H,I). The markers labeled are indicated in the upper left of each photograph. All images are oriented following the same standard: dorsal is upwards in transverse and sagittal sections, and rostral is to the left in sagittal sections. The neuromeric boundaries and main brain subdivisions are indicated to assist in the precise localization of the labeling. The levels of the transverse sections (A,K,L) are indicated in photograph (J), the level of (G) is indicated in (F), and the level of (M) is indicated in (N). Scale bars = 50 μm. See list for abbreviations.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4530589&req=5

Figure 4: Expression of thalamic markers at embryonic stages 40/41. Microphotographs of transverse (A–E,G–I,K–M) or sagittal (F,J,N,O) sections of embryos at stages 40/41. In all cases, photographs correspond to combination of ISH (purple) with IHC (brown), except for a double fluorescent ISH (red) and IHC (green) panel (E) and two single ISH (purple; H,I). The markers labeled are indicated in the upper left of each photograph. All images are oriented following the same standard: dorsal is upwards in transverse and sagittal sections, and rostral is to the left in sagittal sections. The neuromeric boundaries and main brain subdivisions are indicated to assist in the precise localization of the labeling. The levels of the transverse sections (A,K,L) are indicated in photograph (J), the level of (G) is indicated in (F), and the level of (M) is indicated in (N). Scale bars = 50 μm. See list for abbreviations.

Mentions: To describe the molecular patterns that progressively characterize the thalamic territory as embryonic development proceeds, we will present results obtained in whole mount specimens and in series of transverse, sagittal, and horizontal sections. We performed two-color ISH or IHC, and combinations of ISH and IHC to identify landmarks (like the Zli) and obtain precise spatial gene expression maps in the developing thalamus and adjacent regions. We analyzed the embryonic development starting at stage 29/30, when [3H]-thymidine studies indicated that in Xenopus distinct parts of the diencephalon, including the epithalamus, arise (Tay and Straznicky, 1982). From these early stages until stage 40, in which neuron generation appears in the thalamus (Zeng et al., 2008), the prepatterning of the thalamus and the formation of the Zli take place. Figures 1 and 2 illustrate the expression patterns observed at early stages. During the late embryonic stages (stages 40–45) the patterning of the thalamus is established, and the features of the different gene expression patterns are shown in Figures 3–5. Schematic representations of the main expression patterns occurring during prepatterning (Figure 6) and the different patterns observed along the embryonic period are drawn in a lateral view of the forebrain (Figure 7). In addition, we will comment on the expression observed in cells in or close to the ventricular lining (ventricular zone; vz) and in migrated cells in the external zones (mantle zone; mz). A summary diagram of the combinatorial gene code found in each thalamic region is provided (Figure 8).


Prepatterning and patterning of the thalamus along embryonic development of Xenopus laevis.

Bandín S, Morona R, González A - Front Neuroanat (2015)

Expression of thalamic markers at embryonic stages 40/41. Microphotographs of transverse (A–E,G–I,K–M) or sagittal (F,J,N,O) sections of embryos at stages 40/41. In all cases, photographs correspond to combination of ISH (purple) with IHC (brown), except for a double fluorescent ISH (red) and IHC (green) panel (E) and two single ISH (purple; H,I). The markers labeled are indicated in the upper left of each photograph. All images are oriented following the same standard: dorsal is upwards in transverse and sagittal sections, and rostral is to the left in sagittal sections. The neuromeric boundaries and main brain subdivisions are indicated to assist in the precise localization of the labeling. The levels of the transverse sections (A,K,L) are indicated in photograph (J), the level of (G) is indicated in (F), and the level of (M) is indicated in (N). Scale bars = 50 μm. See list for abbreviations.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4530589&req=5

Figure 4: Expression of thalamic markers at embryonic stages 40/41. Microphotographs of transverse (A–E,G–I,K–M) or sagittal (F,J,N,O) sections of embryos at stages 40/41. In all cases, photographs correspond to combination of ISH (purple) with IHC (brown), except for a double fluorescent ISH (red) and IHC (green) panel (E) and two single ISH (purple; H,I). The markers labeled are indicated in the upper left of each photograph. All images are oriented following the same standard: dorsal is upwards in transverse and sagittal sections, and rostral is to the left in sagittal sections. The neuromeric boundaries and main brain subdivisions are indicated to assist in the precise localization of the labeling. The levels of the transverse sections (A,K,L) are indicated in photograph (J), the level of (G) is indicated in (F), and the level of (M) is indicated in (N). Scale bars = 50 μm. See list for abbreviations.
Mentions: To describe the molecular patterns that progressively characterize the thalamic territory as embryonic development proceeds, we will present results obtained in whole mount specimens and in series of transverse, sagittal, and horizontal sections. We performed two-color ISH or IHC, and combinations of ISH and IHC to identify landmarks (like the Zli) and obtain precise spatial gene expression maps in the developing thalamus and adjacent regions. We analyzed the embryonic development starting at stage 29/30, when [3H]-thymidine studies indicated that in Xenopus distinct parts of the diencephalon, including the epithalamus, arise (Tay and Straznicky, 1982). From these early stages until stage 40, in which neuron generation appears in the thalamus (Zeng et al., 2008), the prepatterning of the thalamus and the formation of the Zli take place. Figures 1 and 2 illustrate the expression patterns observed at early stages. During the late embryonic stages (stages 40–45) the patterning of the thalamus is established, and the features of the different gene expression patterns are shown in Figures 3–5. Schematic representations of the main expression patterns occurring during prepatterning (Figure 6) and the different patterns observed along the embryonic period are drawn in a lateral view of the forebrain (Figure 7). In addition, we will comment on the expression observed in cells in or close to the ventricular lining (ventricular zone; vz) and in migrated cells in the external zones (mantle zone; mz). A summary diagram of the combinatorial gene code found in each thalamic region is provided (Figure 8).

Bottom Line: The largely conserved expressions of Nkx2.2 in the rostral thalamic domain vs.Gbx2 and Ngn2 (among others) in the caudal domain strongly suggest the role of Shh as morphogen in the amphibian thalamus.All these data showed that the molecular characteristics observed during preparttening and patterning in the thalamus of the anuran Xenopus (anamniote) share many features with those described during thalamic development in amniotes (common patterns in tetrapods) but also with zebrafish, strengthening the idea of a basic organization of this diencephalic region across vertebrates.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Biology, Department of Cell Biology, University Complutense Madrid, Spain.

ABSTRACT
Previous developmental studies of the thalamus (alar part of the diencephalic prosomere p2) have defined the molecular basis for the acquisition of the thalamic competence (preparttening), the subsequent formation of the secondary organizer in the zona limitans intrathalamica, and the early specification of two anteroposterior domains (rostral and caudal progenitor domains) in response to inducing activities and that are shared in birds and mammals. In the present study we have analyzed the embryonic development of the thalamus in the anuran Xenopus laevis to determine conserved or specific features in the amphibian diencephalon. From early embryonic stages to the beginning of the larval period, the expression patterns of 22 markers were analyzed by means of combined In situ hybridization (ISH) and immunohistochemical techniques. The early genoarchitecture observed in the diencephalon allowed us to discern the boundaries of the thalamus with the prethalamus, pretectum, and epithalamus. Common molecular features were observed in the thalamic prepatterning among vertebrates in which Wnt3a, Fez, Pax6 and Xiro1 expression were of particular importance in Xenopus. The formation of the zona limitans intrathalamica was observed, as in other vertebrates, by the progressive expression of Shh. The largely conserved expressions of Nkx2.2 in the rostral thalamic domain vs. Gbx2 and Ngn2 (among others) in the caudal domain strongly suggest the role of Shh as morphogen in the amphibian thalamus. All these data showed that the molecular characteristics observed during preparttening and patterning in the thalamus of the anuran Xenopus (anamniote) share many features with those described during thalamic development in amniotes (common patterns in tetrapods) but also with zebrafish, strengthening the idea of a basic organization of this diencephalic region across vertebrates.

No MeSH data available.


Related in: MedlinePlus