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The anatomy of the foveola reinvestigated

OBJECTIVE: In the foveola of the eye, photoreceptors and Müller cells with a unique morphology have been described, but little is known about their 3D structure and orientation. Considering that there is an angle-dependent change in the foveolar photoreceptor response for the same light beam, known...

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Autores principales: Tschulakow, Alexander V., Oltrup, Theo, Bende, Thomas, Schmelzle, Sebastian, Schraermeyer, Ulrich
Formato: Online Artículo Texto
Lenguaje:English
Publicado: PeerJ Inc. 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5853608/
https://www.ncbi.nlm.nih.gov/pubmed/29576957
http://dx.doi.org/10.7717/peerj.4482
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author Tschulakow, Alexander V.
Oltrup, Theo
Bende, Thomas
Schmelzle, Sebastian
Schraermeyer, Ulrich
author_facet Tschulakow, Alexander V.
Oltrup, Theo
Bende, Thomas
Schmelzle, Sebastian
Schraermeyer, Ulrich
author_sort Tschulakow, Alexander V.
collection PubMed
description OBJECTIVE: In the foveola of the eye, photoreceptors and Müller cells with a unique morphology have been described, but little is known about their 3D structure and orientation. Considering that there is an angle-dependent change in the foveolar photoreceptor response for the same light beam, known as the Stiles Crawford Effect of the first kind (SCE I), which is still not fully understood, a detailed analysis of the anatomy of the foveolar cells might help to clarify this phenomenon. METHODS: Serial semithin and ultrathin sections, and focused ion beam (FIB) tomography were prepared from 32 foveolae from monkeys (Macaca fascicularis) and humans. Foveolae were also analyzed under the electron microscope. Serial sections and FIB analysis were then used to construct 3D models of central Müller and photoreceptor cells. In addition, we measured the transmission of collimated light under the light microscope at different angles after it had passed through human foveae from flat mounted isolated retinae. RESULTS: In monkeys, outer segments of central foveolar cones are twice as long as those from parafoveal cones and do not run completely parallel to the incident light. Unique Müller cells are present in the central foveolae (area of 200 µm in diameter) of humans and monkeys. Light entering the fovea center, which is composed only of cones and Müller cells, at an angle of 0° causes a very bright spot after passing through this area. However, when the angle of the light beam is changed to 10°, less light is measured after transpasssing through the retina, the foveolar center becomes darker and the SCE-like phenomenon is directly visible. Measurements of the intensities of light transmission through the central foveola for the incident angles 0 and 10° resemble the relative luminance efficiency for narrow light bundles as a function of the location where the beam enters the pupil as reported by Stiles and Crawford. The effect persisted after carefully brushing away the outer segments. CONCLUSION: We show that unique cones and Müller cells with light fibre-like properties are present in the center of the fovea. These unique Müller cells cause an angle dependent, SCE-like drop in the intensity of light guided through the foveola. Outer segments from the foveolar cones of monkeys are not straight.
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spelling pubmed-58536082018-03-24 The anatomy of the foveola reinvestigated Tschulakow, Alexander V. Oltrup, Theo Bende, Thomas Schmelzle, Sebastian Schraermeyer, Ulrich PeerJ Biophysics OBJECTIVE: In the foveola of the eye, photoreceptors and Müller cells with a unique morphology have been described, but little is known about their 3D structure and orientation. Considering that there is an angle-dependent change in the foveolar photoreceptor response for the same light beam, known as the Stiles Crawford Effect of the first kind (SCE I), which is still not fully understood, a detailed analysis of the anatomy of the foveolar cells might help to clarify this phenomenon. METHODS: Serial semithin and ultrathin sections, and focused ion beam (FIB) tomography were prepared from 32 foveolae from monkeys (Macaca fascicularis) and humans. Foveolae were also analyzed under the electron microscope. Serial sections and FIB analysis were then used to construct 3D models of central Müller and photoreceptor cells. In addition, we measured the transmission of collimated light under the light microscope at different angles after it had passed through human foveae from flat mounted isolated retinae. RESULTS: In monkeys, outer segments of central foveolar cones are twice as long as those from parafoveal cones and do not run completely parallel to the incident light. Unique Müller cells are present in the central foveolae (area of 200 µm in diameter) of humans and monkeys. Light entering the fovea center, which is composed only of cones and Müller cells, at an angle of 0° causes a very bright spot after passing through this area. However, when the angle of the light beam is changed to 10°, less light is measured after transpasssing through the retina, the foveolar center becomes darker and the SCE-like phenomenon is directly visible. Measurements of the intensities of light transmission through the central foveola for the incident angles 0 and 10° resemble the relative luminance efficiency for narrow light bundles as a function of the location where the beam enters the pupil as reported by Stiles and Crawford. The effect persisted after carefully brushing away the outer segments. CONCLUSION: We show that unique cones and Müller cells with light fibre-like properties are present in the center of the fovea. These unique Müller cells cause an angle dependent, SCE-like drop in the intensity of light guided through the foveola. Outer segments from the foveolar cones of monkeys are not straight. PeerJ Inc. 2018-03-12 /pmc/articles/PMC5853608/ /pubmed/29576957 http://dx.doi.org/10.7717/peerj.4482 Text en ©2018 Tschulakow et al. http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited.
spellingShingle Biophysics
Tschulakow, Alexander V.
Oltrup, Theo
Bende, Thomas
Schmelzle, Sebastian
Schraermeyer, Ulrich
The anatomy of the foveola reinvestigated
title The anatomy of the foveola reinvestigated
title_full The anatomy of the foveola reinvestigated
title_fullStr The anatomy of the foveola reinvestigated
title_full_unstemmed The anatomy of the foveola reinvestigated
title_short The anatomy of the foveola reinvestigated
title_sort anatomy of the foveola reinvestigated
topic Biophysics
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5853608/
https://www.ncbi.nlm.nih.gov/pubmed/29576957
http://dx.doi.org/10.7717/peerj.4482
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