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Ocellar structure and neural innervation in the honeybee.

Hung YS, Ibbotson MR - Front Neuroanat (2014)

Bottom Line: In addition, we established which ocellar retinas provide the input to five pairs of large ocellar descending neurons.We found that four of the neuron pairs have their dendritic fields in the dorsal retinas of the lateral ocelli, while the fifth has fine dendrites in the ventral retina.One of the neuron pairs also sends very fine dendrites into the border region between the dorsal and ventral retinas of the median ocellus.

View Article: PubMed Central - PubMed

Affiliation: National Vision Research Institute, Australian College of Optometry Carlton, VIC, Australia ; Department of Optometry and Vision Sciences, Centre of Excellence for Integrative Brain Function, University of Melbourne Parkville, VIC, Australia.

ABSTRACT
Honeybees have a visual system composed of three ocelli (simple eyes) located on the top of the head, in addition to two large compound eyes. Although experiments have been conducted to investigate the role of the ocelli within the visual system, their optical characteristics, and function remain controversial. In this study, we created three-dimensional (3-D) reconstructions of the honeybee ocelli, conducted optical measurements and filled ocellar descending neurons to assist in determining the role of ocelli in honeybees. In both the median and lateral ocelli, the ocellar retinas can be divided into dorsal and ventral parts. Using the 3-D model we were able to assess the viewing angles of the retinas. The dorsal retinas view the horizon while the ventral retinas view the sky, suggesting quite different roles in attitude control. We used the hanging drop technique to assess the spatial resolution of the retinas. The lateral ocelli have significantly higher spatial resolution compared to the median ocellus. In addition, we established which ocellar retinas provide the input to five pairs of large ocellar descending neurons. We found that four of the neuron pairs have their dendritic fields in the dorsal retinas of the lateral ocelli, while the fifth has fine dendrites in the ventral retina. One of the neuron pairs also sends very fine dendrites into the border region between the dorsal and ventral retinas of the median ocellus.

No MeSH data available.


Related in: MedlinePlus

3-D reconstruction of the honeybee lateral ocellus. (A,B) frontal views of the lateral ocellar lens and retinas. (A) the inner surface of the lens (l, shown in yellow) of the lateral ocellus is asymmetrical, the dorsal (dr, shown in purple), and ventral (vr, blue) retinas follow the inner surface of the lens and are pointing toward the midline of the brain. (C–F) Simulation of the rolling movement of the model. The ocelli are viewed from the side of the head. To the left the ocelli are dorsal. To the extreme right, the head has been rolled downwards by 90° to reveal all three ocellar regions (only the left ocellar retinas are present). (C) A lateral view of the lateral ocellus: only the dorsal retina can be observed. (F) A dorsal view of the three ocelli: only the ventral retina can be observed. Abbreviations: A, anterior; D, dorsal; L, lateral; LO, lateral ocellus; MO, median ocellus.
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Figure 3: 3-D reconstruction of the honeybee lateral ocellus. (A,B) frontal views of the lateral ocellar lens and retinas. (A) the inner surface of the lens (l, shown in yellow) of the lateral ocellus is asymmetrical, the dorsal (dr, shown in purple), and ventral (vr, blue) retinas follow the inner surface of the lens and are pointing toward the midline of the brain. (C–F) Simulation of the rolling movement of the model. The ocelli are viewed from the side of the head. To the left the ocelli are dorsal. To the extreme right, the head has been rolled downwards by 90° to reveal all three ocellar regions (only the left ocellar retinas are present). (C) A lateral view of the lateral ocellus: only the dorsal retina can be observed. (F) A dorsal view of the three ocelli: only the ventral retina can be observed. Abbreviations: A, anterior; D, dorsal; L, lateral; LO, lateral ocellus; MO, median ocellus.

Mentions: From the frontal serial sections, we were able to construct a 3-D model of the honeybee ocellar lenses and retinas (Figures 1A,B). The lens and the retinas of the median ocellus project posteriorly while the lateral ocelli project slightly ventrally and toward the midline of the brain (Figures 1A,B). While sections of the three ocelli illustrate both their internal and external morphologies (Figures 1C,D), the 3-D models of the ocellar lenses and the retinal tissue that lies below the lenses also help to reveal the viewing angles of each ocellus (Figures 2, 3). Combining the results from the 3-D reconstructions and the 2-D sections, we provide a complete visualization of the retinal structures and their relation to the lenses.


Ocellar structure and neural innervation in the honeybee.

Hung YS, Ibbotson MR - Front Neuroanat (2014)

3-D reconstruction of the honeybee lateral ocellus. (A,B) frontal views of the lateral ocellar lens and retinas. (A) the inner surface of the lens (l, shown in yellow) of the lateral ocellus is asymmetrical, the dorsal (dr, shown in purple), and ventral (vr, blue) retinas follow the inner surface of the lens and are pointing toward the midline of the brain. (C–F) Simulation of the rolling movement of the model. The ocelli are viewed from the side of the head. To the left the ocelli are dorsal. To the extreme right, the head has been rolled downwards by 90° to reveal all three ocellar regions (only the left ocellar retinas are present). (C) A lateral view of the lateral ocellus: only the dorsal retina can be observed. (F) A dorsal view of the three ocelli: only the ventral retina can be observed. Abbreviations: A, anterior; D, dorsal; L, lateral; LO, lateral ocellus; MO, median ocellus.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928595&req=5

Figure 3: 3-D reconstruction of the honeybee lateral ocellus. (A,B) frontal views of the lateral ocellar lens and retinas. (A) the inner surface of the lens (l, shown in yellow) of the lateral ocellus is asymmetrical, the dorsal (dr, shown in purple), and ventral (vr, blue) retinas follow the inner surface of the lens and are pointing toward the midline of the brain. (C–F) Simulation of the rolling movement of the model. The ocelli are viewed from the side of the head. To the left the ocelli are dorsal. To the extreme right, the head has been rolled downwards by 90° to reveal all three ocellar regions (only the left ocellar retinas are present). (C) A lateral view of the lateral ocellus: only the dorsal retina can be observed. (F) A dorsal view of the three ocelli: only the ventral retina can be observed. Abbreviations: A, anterior; D, dorsal; L, lateral; LO, lateral ocellus; MO, median ocellus.
Mentions: From the frontal serial sections, we were able to construct a 3-D model of the honeybee ocellar lenses and retinas (Figures 1A,B). The lens and the retinas of the median ocellus project posteriorly while the lateral ocelli project slightly ventrally and toward the midline of the brain (Figures 1A,B). While sections of the three ocelli illustrate both their internal and external morphologies (Figures 1C,D), the 3-D models of the ocellar lenses and the retinal tissue that lies below the lenses also help to reveal the viewing angles of each ocellus (Figures 2, 3). Combining the results from the 3-D reconstructions and the 2-D sections, we provide a complete visualization of the retinal structures and their relation to the lenses.

Bottom Line: In addition, we established which ocellar retinas provide the input to five pairs of large ocellar descending neurons.We found that four of the neuron pairs have their dendritic fields in the dorsal retinas of the lateral ocelli, while the fifth has fine dendrites in the ventral retina.One of the neuron pairs also sends very fine dendrites into the border region between the dorsal and ventral retinas of the median ocellus.

View Article: PubMed Central - PubMed

Affiliation: National Vision Research Institute, Australian College of Optometry Carlton, VIC, Australia ; Department of Optometry and Vision Sciences, Centre of Excellence for Integrative Brain Function, University of Melbourne Parkville, VIC, Australia.

ABSTRACT
Honeybees have a visual system composed of three ocelli (simple eyes) located on the top of the head, in addition to two large compound eyes. Although experiments have been conducted to investigate the role of the ocelli within the visual system, their optical characteristics, and function remain controversial. In this study, we created three-dimensional (3-D) reconstructions of the honeybee ocelli, conducted optical measurements and filled ocellar descending neurons to assist in determining the role of ocelli in honeybees. In both the median and lateral ocelli, the ocellar retinas can be divided into dorsal and ventral parts. Using the 3-D model we were able to assess the viewing angles of the retinas. The dorsal retinas view the horizon while the ventral retinas view the sky, suggesting quite different roles in attitude control. We used the hanging drop technique to assess the spatial resolution of the retinas. The lateral ocelli have significantly higher spatial resolution compared to the median ocellus. In addition, we established which ocellar retinas provide the input to five pairs of large ocellar descending neurons. We found that four of the neuron pairs have their dendritic fields in the dorsal retinas of the lateral ocelli, while the fifth has fine dendrites in the ventral retina. One of the neuron pairs also sends very fine dendrites into the border region between the dorsal and ventral retinas of the median ocellus.

No MeSH data available.


Related in: MedlinePlus