Podcast
Questions and Answers
What is the initial function of sonic hedgehog (SHH) in the development of the eye field?
What is the initial function of sonic hedgehog (SHH) in the development of the eye field?
- Suppressing the formation of the lens from surface ectoderm.
- Dividing the single eye field into two separate optic primordia. (correct)
- Promoting the expression of PAX6 throughout the anterior neural ridge.
- Inhibiting PAX2 expression to prevent optic stalk formation.
How does SHH contribute to the differentiation of the optic stalk?
How does SHH contribute to the differentiation of the optic stalk?
- By directly inducing the formation of the lens.
- By upregulating the expression of PAX2 in the midline. (correct)
- By inhibiting the expression of PAX6 in the midline.
- By repressing the differentiation of the neural retinal layer.
A mutation in the PAX2 gene is most likely to result in:
A mutation in the PAX2 gene is most likely to result in:
- Aniridia (absence of iris).
- Anophthalmia (absence of eye).
- Optic nerve colobomas. (correct)
- Microphthalmia (abnormally small eye).
What role do FGFs secreted by the surface ectoderm play in eye development?
What role do FGFs secreted by the surface ectoderm play in eye development?
If the surrounding mesenchyme is disrupted, preventing the secretion of TGF-β family members, which of the following is most likely to occur?
If the surrounding mesenchyme is disrupted, preventing the secretion of TGF-β family members, which of the following is most likely to occur?
CHX10 is a transcription factor that primarily directs:
CHX10 is a transcription factor that primarily directs:
What is the primary role of MITF in the development of the eye?
What is the primary role of MITF in the development of the eye?
What is the effect of a mutation in PAX6 on eye development?
What is the effect of a mutation in PAX6 on eye development?
How do external signals influence the expression of downstream genes within the optic cup layers?
How do external signals influence the expression of downstream genes within the optic cup layers?
PAX6 is initially expressed in which specific region during eye development?
PAX6 is initially expressed in which specific region during eye development?
What would be the most likely consequence of a mutation preventing the secretion of SHH from the prechordal plate?
What would be the most likely consequence of a mutation preventing the secretion of SHH from the prechordal plate?
What process relies on epi-mesenchymal interactions with signaling molecules after the eye field is initially made by PAX6?
What process relies on epi-mesenchymal interactions with signaling molecules after the eye field is initially made by PAX6?
Why is the secretion of SHH from the prechordal plate essential for normal eye development?
Why is the secretion of SHH from the prechordal plate essential for normal eye development?
In cases of Aniridia caused by PAX6 mutations, what specific developmental process is primarily affected?
In cases of Aniridia caused by PAX6 mutations, what specific developmental process is primarily affected?
If the surface ectoderm failed to secrete FGFs during eye development, which of the following would be the most direct consequence?
If the surface ectoderm failed to secrete FGFs during eye development, which of the following would be the most direct consequence?
How do mutations in the transcription factors CHX10 and MITF distinctly affect eye development?
How do mutations in the transcription factors CHX10 and MITF distinctly affect eye development?
Considering the role of PAX6 and SHH in early eye development, what might be a potential outcome if PAX6 expression was not properly inhibited in the midline?
Considering the role of PAX6 and SHH in early eye development, what might be a potential outcome if PAX6 expression was not properly inhibited in the midline?
What is the relationship between the timing of PAX6 expression and the role of SHH in early eye development?
What is the relationship between the timing of PAX6 expression and the role of SHH in early eye development?
The differentiation of retinal layers is controlled by different signaling molecules. How do FGFs and TGF-β family members coordinate this process?
The differentiation of retinal layers is controlled by different signaling molecules. How do FGFs and TGF-β family members coordinate this process?
How do the roles of CHX10 and MITF demonstrate the specificity of transcription factors in eye development?
How do the roles of CHX10 and MITF demonstrate the specificity of transcription factors in eye development?
Flashcards
PAX6
PAX6
Transcription factor initially expressed as a band in the center of the anterior neural ridge during the 3rd week of gestation; critical for eye development.
Sonic Hedgehog (SHH)
Sonic Hedgehog (SHH)
Signaling molecule secreted by the prechordal plate that divides the single eye field into two optic primordia.
SHH's role in eye development
SHH's role in eye development
Inhibits expression of PAX6 in the midline, creating a boundary between the developing eyes
PAX2 Function
PAX2 Function
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PAX2 Mutations
PAX2 Mutations
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PAX6 Mutations
PAX6 Mutations
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FGFs in Eye Development
FGFs in Eye Development
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TGF-b in Eye Development
TGF-b in Eye Development
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CHX10
CHX10
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MITF
MITF
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Study Notes
- Gestation lasts approximately 3 weeks.
- PAX6 is initially expressed as a band in the center of the anterior neural ridge.
- The single eye field separates into two optic primordia.
- Separation is mediated by sonic hedgehog (SHH) secreted by the prechordal plate.
- SHH inhibits the expression of PAX6 in the midline, creating a boundary between the developing eyes.
- SHH upregulates the expression of PAX2 in the midline, which is involved in the differentiation of the optic stalk.
- PAX6 continues to regulate the differentiation of the eyes themselves.
- It is expressed in the optic cup.
- It is expressed in the overlying surface ectoderm that will form the lens.
- PAX2 mutations can cause optic nerve colobomas.
- PAX6 mutations can cause aniridia (absence of iris).
- PAX6 mutations may contribute to anophthalmia and microphthalmia.
- Epi-mesenchymal interactions involving signaling molecules are critical for subsequent eye patterning after the eye field is established by PAX6.
- Fibroblast growth factors (FGFs) secreted by the surface ectoderm in the lens-forming region promote the differentiation of the neural retinal layer (inner optic cup).
- TGF-β family members, secreted by the surrounding mesenchyme, promote the differentiation of the pigmented retinal layer (outer optic cup).
- External signals regulate downstream genes within the optic cup layers.
- The transcription factor CHX10 is expressed
- CHX10 directs the continued differentiation of the neural retina.
- The transcription factor MITF is expressed
- MITF directs the continued differentiation of the pigmented retina.
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