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Imaging heart development using high-resolution episcopic microscopy.

Mohun TJ, Weninger WJ - Curr. Opin. Genet. Dev. (2011)

Bottom Line: Development of the heart in vertebrate embryos is a complex process in which the organ is continually remodelled as chambers are formed, valves sculpted and connections established to the developing vascular system.A recurrent challenge in this work is how to integrate studies as diverse as those of cardiac gene function and regulation with an appreciation of the localised interactions between cardiac tissues not to mention the manner in which both may be affected by cardiac function itself.Meeting this challenge requires an accurate way to analyse the changes in 3D morphology of the developing heart, which can be swift or protracted and both dramatic or subtle in consequence.

View Article: PubMed Central - PubMed

Affiliation: MRC National Institute for Medical Research, London, UK. tmohun@nimr.mrc.ac.uk

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(a) 3D models of β-galactosidase expression in an E11.5 Islet1-lacZ embryo, captured by dual wavelength HREM and pseudo-coloured magenta in the whole embryo (left) or white in the heart (right). The latter is eroded in the transverse plane to show expression in the central pharyngeal region (including the dorsal roof of the aortic sac) as well as both proximal and distal walls of the outflow tract. (b) Images obtained by ‘virtual endoscopy’ using HREM data from an E18.5 mouse embryo heart, revealing remarkable details of heart structure. The left panel shows a view of the right atrium from the entrance of the right superior caval vein. Note the smooth ventral floor of the right atrium surrounding the coronary sinus, flanked on one side by the trabeculae of the right atrial appendage and edge of the tricuspid valve on the other. The right panel shows a view of the trabecular lattice within the right atrium, viewed through the tricuspid valve.
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fig0015: (a) 3D models of β-galactosidase expression in an E11.5 Islet1-lacZ embryo, captured by dual wavelength HREM and pseudo-coloured magenta in the whole embryo (left) or white in the heart (right). The latter is eroded in the transverse plane to show expression in the central pharyngeal region (including the dorsal roof of the aortic sac) as well as both proximal and distal walls of the outflow tract. (b) Images obtained by ‘virtual endoscopy’ using HREM data from an E18.5 mouse embryo heart, revealing remarkable details of heart structure. The left panel shows a view of the right atrium from the entrance of the right superior caval vein. Note the smooth ventral floor of the right atrium surrounding the coronary sinus, flanked on one side by the trabeculae of the right atrial appendage and edge of the tricuspid valve on the other. The right panel shows a view of the trabecular lattice within the right atrium, viewed through the tricuspid valve.

Mentions: 3D modelling of gene expression patterns has had an important impact on our understanding of heart morphogenesis by revealing the contributions of different cell lineages either directly (using CRE-mediated recombination to activate reporter genes) or indirectly (using endogenous gene expression patterns as a surrogate for lineage marking). As more marker genes for cardiac cells and tissues are identified, such studies will increasingly allow all aspects of cardiac development to be reassessed. Gene expression studies have almost exclusively relied on staining individual sections, since this has yielded the most sensitive results and allowed investigation of several gene patterns simultaneously. However, as with studies of morphology, reconstruction of the expression data into 3D models inevitably results in significant loss of resolution, in part from the limited frequency of sections but also from the constraints imposed by poor section registration. The finding that HREM can be adapted to detect localised patterns of gene expression revealed by colourimetric stains is therefore potentially important [25••]. Of course, the gains obtained from episcopic imaging may be offset by the loss of signal sensitivity resulting from wholemount rather than section staining procedures. This is undoubtedly the case for later stages of heart development in the mouse where penetration of staining reagents into dense cardiac tissue can be problematic. However, for stages of development up to E11.5–12.5, covering much of the period during which the heart is formed, reasonable staining appears possible and the resulting data can be combined with morphology to produce highly detailed 3D models (Figure 3a).


Imaging heart development using high-resolution episcopic microscopy.

Mohun TJ, Weninger WJ - Curr. Opin. Genet. Dev. (2011)

(a) 3D models of β-galactosidase expression in an E11.5 Islet1-lacZ embryo, captured by dual wavelength HREM and pseudo-coloured magenta in the whole embryo (left) or white in the heart (right). The latter is eroded in the transverse plane to show expression in the central pharyngeal region (including the dorsal roof of the aortic sac) as well as both proximal and distal walls of the outflow tract. (b) Images obtained by ‘virtual endoscopy’ using HREM data from an E18.5 mouse embryo heart, revealing remarkable details of heart structure. The left panel shows a view of the right atrium from the entrance of the right superior caval vein. Note the smooth ventral floor of the right atrium surrounding the coronary sinus, flanked on one side by the trabeculae of the right atrial appendage and edge of the tricuspid valve on the other. The right panel shows a view of the trabecular lattice within the right atrium, viewed through the tricuspid valve.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368266&req=5

fig0015: (a) 3D models of β-galactosidase expression in an E11.5 Islet1-lacZ embryo, captured by dual wavelength HREM and pseudo-coloured magenta in the whole embryo (left) or white in the heart (right). The latter is eroded in the transverse plane to show expression in the central pharyngeal region (including the dorsal roof of the aortic sac) as well as both proximal and distal walls of the outflow tract. (b) Images obtained by ‘virtual endoscopy’ using HREM data from an E18.5 mouse embryo heart, revealing remarkable details of heart structure. The left panel shows a view of the right atrium from the entrance of the right superior caval vein. Note the smooth ventral floor of the right atrium surrounding the coronary sinus, flanked on one side by the trabeculae of the right atrial appendage and edge of the tricuspid valve on the other. The right panel shows a view of the trabecular lattice within the right atrium, viewed through the tricuspid valve.
Mentions: 3D modelling of gene expression patterns has had an important impact on our understanding of heart morphogenesis by revealing the contributions of different cell lineages either directly (using CRE-mediated recombination to activate reporter genes) or indirectly (using endogenous gene expression patterns as a surrogate for lineage marking). As more marker genes for cardiac cells and tissues are identified, such studies will increasingly allow all aspects of cardiac development to be reassessed. Gene expression studies have almost exclusively relied on staining individual sections, since this has yielded the most sensitive results and allowed investigation of several gene patterns simultaneously. However, as with studies of morphology, reconstruction of the expression data into 3D models inevitably results in significant loss of resolution, in part from the limited frequency of sections but also from the constraints imposed by poor section registration. The finding that HREM can be adapted to detect localised patterns of gene expression revealed by colourimetric stains is therefore potentially important [25••]. Of course, the gains obtained from episcopic imaging may be offset by the loss of signal sensitivity resulting from wholemount rather than section staining procedures. This is undoubtedly the case for later stages of heart development in the mouse where penetration of staining reagents into dense cardiac tissue can be problematic. However, for stages of development up to E11.5–12.5, covering much of the period during which the heart is formed, reasonable staining appears possible and the resulting data can be combined with morphology to produce highly detailed 3D models (Figure 3a).

Bottom Line: Development of the heart in vertebrate embryos is a complex process in which the organ is continually remodelled as chambers are formed, valves sculpted and connections established to the developing vascular system.A recurrent challenge in this work is how to integrate studies as diverse as those of cardiac gene function and regulation with an appreciation of the localised interactions between cardiac tissues not to mention the manner in which both may be affected by cardiac function itself.Meeting this challenge requires an accurate way to analyse the changes in 3D morphology of the developing heart, which can be swift or protracted and both dramatic or subtle in consequence.

View Article: PubMed Central - PubMed

Affiliation: MRC National Institute for Medical Research, London, UK. tmohun@nimr.mrc.ac.uk

Show MeSH
Related in: MedlinePlus