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Genetic determinants of hyaloid and retinal vasculature in zebrafish.

Alvarez Y, Cederlund ML, Cottell DC, Bill BR, Ekker SC, Torres-Vazquez J, Weinstein BM, Hyde DR, Vihtelic TS, Kennedy BN - BMC Dev. Biol. (2007)

Bottom Line: Similar to the transient hyaloid vasculature in mammalian embryos, vessels are first found attached to the zebrafish lens at 2.5 days post fertilisation.Finally, we identify 9 genes with cell membrane, extracellular matrix and unknown identity that are necessary for zebrafish hyaloid and retinal vasculature development.Zebrafish have a retinal blood supply with a characteristic developmental and adult morphology.

View Article: PubMed Central - HTML - PubMed

Affiliation: UCD School of Biomolecular, and Biomedical Sciences, University College Dublin, Dublin 4, Ireland. yolanda.alvarez@ucd.ie

ABSTRACT

Background: The retinal vasculature is a capillary network of blood vessels that nourishes the inner retina of most mammals. Developmental abnormalities or microvascular complications in the retinal vasculature result in severe human eye diseases that lead to blindness. To exploit the advantages of zebrafish for genetic, developmental and pharmacological studies of retinal vasculature, we characterised the intraocular vasculature in zebrafish.

Results: We show a detailed morphological and developmental analysis of the retinal blood supply in zebrafish. Similar to the transient hyaloid vasculature in mammalian embryos, vessels are first found attached to the zebrafish lens at 2.5 days post fertilisation. These vessels progressively lose contact with the lens and by 30 days post fertilisation adhere to the inner limiting membrane of the juvenile retina. Ultrastructure analysis shows these vessels to exhibit distinctive hallmarks of mammalian retinal vasculature. For example, smooth muscle actin-expressing pericytes are ensheathed by the basal lamina of the blood vessel, and vesicle vacuolar organelles (VVO), subcellular mediators of vessel-retinal nourishment, are present. Finally, we identify 9 genes with cell membrane, extracellular matrix and unknown identity that are necessary for zebrafish hyaloid and retinal vasculature development.

Conclusion: Zebrafish have a retinal blood supply with a characteristic developmental and adult morphology. Abnormalities of these intraocular vessels are easily observed, enabling application of genetic and chemical approaches in zebrafish to identify molecular regulators of hyaloid and retinal vasculature in development and disease.

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Dynamic development of the hyaloid and retinal vasculature in zebrafish. Shown are fluorescent images of blood vessels on lenses and wholemount retinas dissected from Tg(fli1:EGFP) zebrafish. A: First intraocular vessels are detected at 60 hpf surrounding and attached to the forming lens. B: This vasculature evolves quickly and at 5 dpf covers the lens from the optic disk to the IOC. C: At 19 dpf an intricate network of hyaloid vessels branches around the lens. Some vessels at the posterior lens have lost contact and are attached to the retina (inset). D: At 28 dpf, detachment of the vessels from the lens has progressed anteriorly from the central region and extensive vasculature is found on the inner retina. E: Retina and F: lens from a 60 dpf zebrafish. In this specimen some vessels are attached to the lens although most of them are found on the retina. Inset in F: Overlay of the retina from E pseudo-coloured in red, and the lens from F depicts the complementing network of vessels. G: Retina of another 60 dpf zebrafish with the complete vasculature overlying the inner retina. H: Typical vascular pattern of intraocular vasculature in a 6 month old fish. I: Inner retina of a 22 month old senescent zebrafish showing slightly thinner and more fragile vessels. White circumferences demarcate the lens in A-F. Yellow arrows point from posterior to anterior lens in A-D&F and from dorsal to ventral retina in E&G-I. Scale bars: 50 μm in A-D; 100 μm in E-G and 500 μm in H-I.
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Figure 2: Dynamic development of the hyaloid and retinal vasculature in zebrafish. Shown are fluorescent images of blood vessels on lenses and wholemount retinas dissected from Tg(fli1:EGFP) zebrafish. A: First intraocular vessels are detected at 60 hpf surrounding and attached to the forming lens. B: This vasculature evolves quickly and at 5 dpf covers the lens from the optic disk to the IOC. C: At 19 dpf an intricate network of hyaloid vessels branches around the lens. Some vessels at the posterior lens have lost contact and are attached to the retina (inset). D: At 28 dpf, detachment of the vessels from the lens has progressed anteriorly from the central region and extensive vasculature is found on the inner retina. E: Retina and F: lens from a 60 dpf zebrafish. In this specimen some vessels are attached to the lens although most of them are found on the retina. Inset in F: Overlay of the retina from E pseudo-coloured in red, and the lens from F depicts the complementing network of vessels. G: Retina of another 60 dpf zebrafish with the complete vasculature overlying the inner retina. H: Typical vascular pattern of intraocular vasculature in a 6 month old fish. I: Inner retina of a 22 month old senescent zebrafish showing slightly thinner and more fragile vessels. White circumferences demarcate the lens in A-F. Yellow arrows point from posterior to anterior lens in A-D&F and from dorsal to ventral retina in E&G-I. Scale bars: 50 μm in A-D; 100 μm in E-G and 500 μm in H-I.

Mentions: To characterise the development of the retinal blood supply in zebrafish, eyes of fli1-EGFP transgenic fish from 24 hpf to 22 months old were analysed. By 48 hpf, some EGFP positive cells are present between the lens and the retina (data not shown). These endothelial cells give rise to the first hyaloid vessels, distinguishable by 2.5 dpf as a rudimentary vasculature tightly attached to the lens (Fig 2A). At 5 dpf, the vessels are organized in a hemispherical basket embracing the lens from the central optic disc to the peripheral IOC (Fig 2B). As this vasculature grows around the lens, the vessels rapidly branch and at 19 dpf have formed an intricate network (Fig 2C). Numerous filopodia project from these vessels indicating dynamic patterning by angiogenesis [18].


Genetic determinants of hyaloid and retinal vasculature in zebrafish.

Alvarez Y, Cederlund ML, Cottell DC, Bill BR, Ekker SC, Torres-Vazquez J, Weinstein BM, Hyde DR, Vihtelic TS, Kennedy BN - BMC Dev. Biol. (2007)

Dynamic development of the hyaloid and retinal vasculature in zebrafish. Shown are fluorescent images of blood vessels on lenses and wholemount retinas dissected from Tg(fli1:EGFP) zebrafish. A: First intraocular vessels are detected at 60 hpf surrounding and attached to the forming lens. B: This vasculature evolves quickly and at 5 dpf covers the lens from the optic disk to the IOC. C: At 19 dpf an intricate network of hyaloid vessels branches around the lens. Some vessels at the posterior lens have lost contact and are attached to the retina (inset). D: At 28 dpf, detachment of the vessels from the lens has progressed anteriorly from the central region and extensive vasculature is found on the inner retina. E: Retina and F: lens from a 60 dpf zebrafish. In this specimen some vessels are attached to the lens although most of them are found on the retina. Inset in F: Overlay of the retina from E pseudo-coloured in red, and the lens from F depicts the complementing network of vessels. G: Retina of another 60 dpf zebrafish with the complete vasculature overlying the inner retina. H: Typical vascular pattern of intraocular vasculature in a 6 month old fish. I: Inner retina of a 22 month old senescent zebrafish showing slightly thinner and more fragile vessels. White circumferences demarcate the lens in A-F. Yellow arrows point from posterior to anterior lens in A-D&F and from dorsal to ventral retina in E&G-I. Scale bars: 50 μm in A-D; 100 μm in E-G and 500 μm in H-I.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2169232&req=5

Figure 2: Dynamic development of the hyaloid and retinal vasculature in zebrafish. Shown are fluorescent images of blood vessels on lenses and wholemount retinas dissected from Tg(fli1:EGFP) zebrafish. A: First intraocular vessels are detected at 60 hpf surrounding and attached to the forming lens. B: This vasculature evolves quickly and at 5 dpf covers the lens from the optic disk to the IOC. C: At 19 dpf an intricate network of hyaloid vessels branches around the lens. Some vessels at the posterior lens have lost contact and are attached to the retina (inset). D: At 28 dpf, detachment of the vessels from the lens has progressed anteriorly from the central region and extensive vasculature is found on the inner retina. E: Retina and F: lens from a 60 dpf zebrafish. In this specimen some vessels are attached to the lens although most of them are found on the retina. Inset in F: Overlay of the retina from E pseudo-coloured in red, and the lens from F depicts the complementing network of vessels. G: Retina of another 60 dpf zebrafish with the complete vasculature overlying the inner retina. H: Typical vascular pattern of intraocular vasculature in a 6 month old fish. I: Inner retina of a 22 month old senescent zebrafish showing slightly thinner and more fragile vessels. White circumferences demarcate the lens in A-F. Yellow arrows point from posterior to anterior lens in A-D&F and from dorsal to ventral retina in E&G-I. Scale bars: 50 μm in A-D; 100 μm in E-G and 500 μm in H-I.
Mentions: To characterise the development of the retinal blood supply in zebrafish, eyes of fli1-EGFP transgenic fish from 24 hpf to 22 months old were analysed. By 48 hpf, some EGFP positive cells are present between the lens and the retina (data not shown). These endothelial cells give rise to the first hyaloid vessels, distinguishable by 2.5 dpf as a rudimentary vasculature tightly attached to the lens (Fig 2A). At 5 dpf, the vessels are organized in a hemispherical basket embracing the lens from the central optic disc to the peripheral IOC (Fig 2B). As this vasculature grows around the lens, the vessels rapidly branch and at 19 dpf have formed an intricate network (Fig 2C). Numerous filopodia project from these vessels indicating dynamic patterning by angiogenesis [18].

Bottom Line: Similar to the transient hyaloid vasculature in mammalian embryos, vessels are first found attached to the zebrafish lens at 2.5 days post fertilisation.Finally, we identify 9 genes with cell membrane, extracellular matrix and unknown identity that are necessary for zebrafish hyaloid and retinal vasculature development.Zebrafish have a retinal blood supply with a characteristic developmental and adult morphology.

View Article: PubMed Central - HTML - PubMed

Affiliation: UCD School of Biomolecular, and Biomedical Sciences, University College Dublin, Dublin 4, Ireland. yolanda.alvarez@ucd.ie

ABSTRACT

Background: The retinal vasculature is a capillary network of blood vessels that nourishes the inner retina of most mammals. Developmental abnormalities or microvascular complications in the retinal vasculature result in severe human eye diseases that lead to blindness. To exploit the advantages of zebrafish for genetic, developmental and pharmacological studies of retinal vasculature, we characterised the intraocular vasculature in zebrafish.

Results: We show a detailed morphological and developmental analysis of the retinal blood supply in zebrafish. Similar to the transient hyaloid vasculature in mammalian embryos, vessels are first found attached to the zebrafish lens at 2.5 days post fertilisation. These vessels progressively lose contact with the lens and by 30 days post fertilisation adhere to the inner limiting membrane of the juvenile retina. Ultrastructure analysis shows these vessels to exhibit distinctive hallmarks of mammalian retinal vasculature. For example, smooth muscle actin-expressing pericytes are ensheathed by the basal lamina of the blood vessel, and vesicle vacuolar organelles (VVO), subcellular mediators of vessel-retinal nourishment, are present. Finally, we identify 9 genes with cell membrane, extracellular matrix and unknown identity that are necessary for zebrafish hyaloid and retinal vasculature development.

Conclusion: Zebrafish have a retinal blood supply with a characteristic developmental and adult morphology. Abnormalities of these intraocular vessels are easily observed, enabling application of genetic and chemical approaches in zebrafish to identify molecular regulators of hyaloid and retinal vasculature in development and disease.

Show MeSH
Related in: MedlinePlus