Limits...
The Spemann organizer meets the anterior-most neuroectoderm at the equator of early gastrulae in amphibian species.

Yanagi T, Ito K, Nishihara A, Minamino R, Mori S, Sumida M, Hashimoto C - Dev. Growth Differ. (2015)

Bottom Line: However, we found that this physical contact was already established at the equatorial region of very early gastrula in a wide variety of amphibian species.After the contact is established, the dorsal axis is formed posteriorly, but not anteriorly.The model also implies the possibility of constructing a common model of gastrulation among chordate species.

View Article: PubMed Central - PubMed

Affiliation: JT Biohistory Research Hall, 1-1 Murasaki-cho, Takatsuki, Osaka, 569-1125, Japan; Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan.

Show MeSH

Related in: MedlinePlus

Not dorsal lip but dorsal blastocoel floor acts as anterior organizer in normal development. (A) Schematic representation of blastocoel floor tracing experiments. (B, C) A bead was placed the inside corner of blastocoel at blastopore appearance, and the embryo was dissected sagittally at ACE in Xenopus laevis and Cynops pyrrhogaster, respectively. (D, E) A bead was placed with a small distance from the corner in X. laevis and C. pyrrhogaster, respectively. Arrowheads indicate the tip of Brachet's cleft. (F) Schematic representation of the grafting assay. The embryo at blastopore appearance is grafted ventrally with blastocoel floor tissue of anterior contact establishment (ACE) embryo, and allowed to develop to the tailbud stage. (G, H) X. laevis and C. pyrrhogaster tailbud embryos, respectively. The embryos form a secondary axis containing head structures, as indicated by white brackets. (I, J) The embryo is grafted ventrally with the dorsal lip (Spemann organizer) tissue of ACE embryo, and allowed to develop to the tailbud stage.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4402005&req=5

fig07: Not dorsal lip but dorsal blastocoel floor acts as anterior organizer in normal development. (A) Schematic representation of blastocoel floor tracing experiments. (B, C) A bead was placed the inside corner of blastocoel at blastopore appearance, and the embryo was dissected sagittally at ACE in Xenopus laevis and Cynops pyrrhogaster, respectively. (D, E) A bead was placed with a small distance from the corner in X. laevis and C. pyrrhogaster, respectively. Arrowheads indicate the tip of Brachet's cleft. (F) Schematic representation of the grafting assay. The embryo at blastopore appearance is grafted ventrally with blastocoel floor tissue of anterior contact establishment (ACE) embryo, and allowed to develop to the tailbud stage. (G, H) X. laevis and C. pyrrhogaster tailbud embryos, respectively. The embryos form a secondary axis containing head structures, as indicated by white brackets. (I, J) The embryo is grafted ventrally with the dorsal lip (Spemann organizer) tissue of ACE embryo, and allowed to develop to the tailbud stage.

Mentions: Here, we show that the X. laevis model is fundamentally applicable to a wide variety of amphibian species, and propose a unified model of amphibian gastrulation movement (cf. Fig. 10B). In the model, the anterior organizer is present at the blastocoel floor at the onset of gastrulation, and moves to the equator to make physical contact with the prospective head neuroectoderm through the “subduction and zippering” (S&Z) movement (cf. Fig. 9) during the early step of gastrulation. The blastocoel roof becomes not neural but epidermal tissue after the contact. This physical contact continues to the end of gastrulation movement, indicating that the head is fixed at the dorsal equator of early gastrula so that the A-P axis is formed toward the posterior as the posterior organizer involutes inward (cf. Fig. 10B-6,7). This model of amphibian gastrulation would enable us to make a direct comparison with the gastrulation movements of other chordate species.


The Spemann organizer meets the anterior-most neuroectoderm at the equator of early gastrulae in amphibian species.

Yanagi T, Ito K, Nishihara A, Minamino R, Mori S, Sumida M, Hashimoto C - Dev. Growth Differ. (2015)

Not dorsal lip but dorsal blastocoel floor acts as anterior organizer in normal development. (A) Schematic representation of blastocoel floor tracing experiments. (B, C) A bead was placed the inside corner of blastocoel at blastopore appearance, and the embryo was dissected sagittally at ACE in Xenopus laevis and Cynops pyrrhogaster, respectively. (D, E) A bead was placed with a small distance from the corner in X. laevis and C. pyrrhogaster, respectively. Arrowheads indicate the tip of Brachet's cleft. (F) Schematic representation of the grafting assay. The embryo at blastopore appearance is grafted ventrally with blastocoel floor tissue of anterior contact establishment (ACE) embryo, and allowed to develop to the tailbud stage. (G, H) X. laevis and C. pyrrhogaster tailbud embryos, respectively. The embryos form a secondary axis containing head structures, as indicated by white brackets. (I, J) The embryo is grafted ventrally with the dorsal lip (Spemann organizer) tissue of ACE embryo, and allowed to develop to the tailbud stage.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4402005&req=5

fig07: Not dorsal lip but dorsal blastocoel floor acts as anterior organizer in normal development. (A) Schematic representation of blastocoel floor tracing experiments. (B, C) A bead was placed the inside corner of blastocoel at blastopore appearance, and the embryo was dissected sagittally at ACE in Xenopus laevis and Cynops pyrrhogaster, respectively. (D, E) A bead was placed with a small distance from the corner in X. laevis and C. pyrrhogaster, respectively. Arrowheads indicate the tip of Brachet's cleft. (F) Schematic representation of the grafting assay. The embryo at blastopore appearance is grafted ventrally with blastocoel floor tissue of anterior contact establishment (ACE) embryo, and allowed to develop to the tailbud stage. (G, H) X. laevis and C. pyrrhogaster tailbud embryos, respectively. The embryos form a secondary axis containing head structures, as indicated by white brackets. (I, J) The embryo is grafted ventrally with the dorsal lip (Spemann organizer) tissue of ACE embryo, and allowed to develop to the tailbud stage.
Mentions: Here, we show that the X. laevis model is fundamentally applicable to a wide variety of amphibian species, and propose a unified model of amphibian gastrulation movement (cf. Fig. 10B). In the model, the anterior organizer is present at the blastocoel floor at the onset of gastrulation, and moves to the equator to make physical contact with the prospective head neuroectoderm through the “subduction and zippering” (S&Z) movement (cf. Fig. 9) during the early step of gastrulation. The blastocoel roof becomes not neural but epidermal tissue after the contact. This physical contact continues to the end of gastrulation movement, indicating that the head is fixed at the dorsal equator of early gastrula so that the A-P axis is formed toward the posterior as the posterior organizer involutes inward (cf. Fig. 10B-6,7). This model of amphibian gastrulation would enable us to make a direct comparison with the gastrulation movements of other chordate species.

Bottom Line: However, we found that this physical contact was already established at the equatorial region of very early gastrula in a wide variety of amphibian species.After the contact is established, the dorsal axis is formed posteriorly, but not anteriorly.The model also implies the possibility of constructing a common model of gastrulation among chordate species.

View Article: PubMed Central - PubMed

Affiliation: JT Biohistory Research Hall, 1-1 Murasaki-cho, Takatsuki, Osaka, 569-1125, Japan; Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan.

Show MeSH
Related in: MedlinePlus