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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

On the left is a composite drawing showing the relationship between the five LD neurons in relation to each other and to the ocellar retinas. Outlined are the boundaries of the ocellar lenses and retinas. The gray patch shows the location of the dorsal retina of the median ocellus. On the right are individual drawings of the five cell types, to allow future identification. Scale bar = 100 μm.
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Figure 9: On the left is a composite drawing showing the relationship between the five LD neurons in relation to each other and to the ocellar retinas. Outlined are the boundaries of the ocellar lenses and retinas. The gray patch shows the location of the dorsal retina of the median ocellus. On the right are individual drawings of the five cell types, to allow future identification. Scale bar = 100 μm.

Mentions: The LD neurons can be distinguished from each other by a series of clear features of their central brain morphologies. Given that when the ventral nerve cord is filled, only the descending ocellar neurons climb up into the ocellar tracts and that there are only five very large neurons on each side, it is easy to identify the main axons, cell bodies and the general locations of the dendrites with respect to the ocellar retinas (Figure 8A). It was more difficult to extract the dendritic structures of individual cells from the mass-fills but individual optical sections offered fine detail that allowed reasonable reconstruction over multiple sections (Figure 8B). Figure 9 shows the drawings of the five ocellar descending neurons. Some dendrites below the ocellar retinas in the mass fills proved to be impossible to assign unequivocally to a particular cell. The drawings present the dendrites that categorically belonged to the identified neurons. LD1 has a very distinctive branching pattern in the deutocerebrum, with a large branch that descends toward the suboesophageal ganglion. LD2 also has bushy dendrites in the deutocerebrum but without a single large branch. LD3 has a smaller axon and very fine dendrites in the ocellus. LD4 is the only neuron that descends into the same side of the ventral nerve cord as the ocellus that provides its input. LD5 is very characteristic because before it ascends the ocellar tract it swings very significantly to the contralateral side of the tracts.


Ocellar structure and neural innervation in the honeybee.

Hung YS, Ibbotson MR - Front Neuroanat (2014)

On the left is a composite drawing showing the relationship between the five LD neurons in relation to each other and to the ocellar retinas. Outlined are the boundaries of the ocellar lenses and retinas. The gray patch shows the location of the dorsal retina of the median ocellus. On the right are individual drawings of the five cell types, to allow future identification. Scale bar = 100 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 9: On the left is a composite drawing showing the relationship between the five LD neurons in relation to each other and to the ocellar retinas. Outlined are the boundaries of the ocellar lenses and retinas. The gray patch shows the location of the dorsal retina of the median ocellus. On the right are individual drawings of the five cell types, to allow future identification. Scale bar = 100 μm.
Mentions: The LD neurons can be distinguished from each other by a series of clear features of their central brain morphologies. Given that when the ventral nerve cord is filled, only the descending ocellar neurons climb up into the ocellar tracts and that there are only five very large neurons on each side, it is easy to identify the main axons, cell bodies and the general locations of the dendrites with respect to the ocellar retinas (Figure 8A). It was more difficult to extract the dendritic structures of individual cells from the mass-fills but individual optical sections offered fine detail that allowed reasonable reconstruction over multiple sections (Figure 8B). Figure 9 shows the drawings of the five ocellar descending neurons. Some dendrites below the ocellar retinas in the mass fills proved to be impossible to assign unequivocally to a particular cell. The drawings present the dendrites that categorically belonged to the identified neurons. LD1 has a very distinctive branching pattern in the deutocerebrum, with a large branch that descends toward the suboesophageal ganglion. LD2 also has bushy dendrites in the deutocerebrum but without a single large branch. LD3 has a smaller axon and very fine dendrites in the ocellus. LD4 is the only neuron that descends into the same side of the ventral nerve cord as the ocellus that provides its input. LD5 is very characteristic because before it ascends the ocellar tract it swings very significantly to the contralateral side of the tracts.

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