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Sagittal (midline) section at the optic chiasm of
a Noi mutant two-day-old zebrafish embryo showing
that the optic nerve axons from the two eyes are
not discrete as they are in the normal embryo
(B0001093C). The optic chiasm is the point where
the axons cross the midline toward their target
brain regions.
Credit: R. MacDonald & S. Wilson

Zebrafish optic chiasm

Dorsal view of the head region in a zebrafish
embryo which has been stained to show neuron
development in the epiphysial region of the
diencephalon, part of the developing forebrain.
This is the region where neurons first develop in
the forebrain. In this 'floating head' mutant,
neurons which should be seen at this stage (see
wildtype B0001159C) are missing from this area.

Zebrafish eye development

This differential interference contrast image
shows a section through the eye of a three-day old
zebrafish embryo. At this stage of development,
the nerve cells in the retina have begun to
separate into different layers. The outer layer of
cells are stained black with a marker for
photoreceptor cells, the neurons that respond to
light. (credit: R. MacDonald & S. Wilson) Biomedical Image Awards 1998.

Sagittal (midline) section at the optic chiasm of
a normal two-day-old zebrafish embryo showing two
distinct bundles of optic nerve axons from the two
eyes. This is the point where they cross the
midline toward their target brain regions.
(See B0001083C for wholemount image)

Credit: R. MacDonald & S. Wilson

Light microscope image of a zebrafish embryo
which has been injected with Sonic Hedgehog (shh)
RNA at an earlier stage. The embryo has been
stained with an antibody to Pax6 protein which
indicates early brain and eye development. In this
case, expression of the Pax6 protein has been
inhibited by shh, leading to abnormal development.
(Normal B1091C) Credit: R. MacDonald & S. Wilson

Lateral view of the head region in a zebrafish
embryo which shows neuronal structure in the
epiphysial region of the diencephalon, part of
the developing forebrain. This is the region where
where neurons first develop in the forebrain.
Here, axons labelled with diI can be seen
extending from epiphysial projection neurons.

Retinal ganglion cell axons cross at the optic chiasm as they make their way to the to the optic tectum. Confocal micrograph of the brain of a transgenic 60 hour old zebrafish embryo viewed from a ventral aspect. Some neurons express the green fluorescent protein (GFP) - (green) under the control of a specific promotor, which drives expression in retinal ganglion cells, neuromasts, habenulae and the optic tectum. Tracts and axons have been labeled using antibodies against tubulin (red). 




Width of image is 500 micrometres

Eye development, zebrafish

A composition showing dorsal views of an undissected and dissected 4 days post fertilisation zebrafish brain. These embryos have been labelled with anti-acetylated tubulin antibody(green) that labels neuronal tracts and anti-SV2(magenta) that stains neuropil.

Neuropil is a region between neuronal cell bodies in the gray matter of the brain and blood-brain barrier (i.e. the central nervous system). It consists of a dense tangle of axon terminals, dendrites and glial cell processes. It is where synaptic connections are formed between branches of axons and dendrites.

Zebrafish embryo

The lateral line is a sensory system in fish composed of neuromast cells, which detect vibrations in the water. This image shows the development of the lateral line in a 55 hour old zebrafish embryo containing a mutated form of the gene<I> lef1</I>. The lateral line is produced by a cluster of migratory cells called the posterior lateral line primordium (PLLP), and<I> lef1</I> is a Wnt-pathway transcription factor required to maintain proliferation in the PLLP progenitor pool as the primordium migrates along the tail, periodically depositing neuromasts (green). The nuclei (DNA storage site) of cells of the PLPP are seen in red. 

Width of image is 300 micrometres.

Zebrafish posterior lateral line development

Transverse section of brain and eyes of a zebrafish embryo 3 days post fertilization. The retinal ganglion cell layer of the retina and the optical neurons projecting to the optic tectum, the visual processing centre of the brain, are seen in green. Nuclei are counterstained with DAPI (magenta).

Width of image is 500 micrometres.

Transverse section of brain and eyes, Zebrafish model

A ventral view of a 60 hours post fertilisation transgenic zebrafish embryo. The embryo has been has been labelled with anti GFP(green) and anti-acetylated tubulin antibody(red) that labels neuronal tracts. This transgenic line Brn3a:GFP expresses GFP in many cells within the brain and neural retina. From this aspect the retinal ganglion cells and their axons which form the optic nerve can be seen projecting to the midline and crossing to travel dorsally and innervate the contralateral optic tectum habenula neurons, neurons in the optic tectum. The sensory neuromast cells are also beautifully labelled, these cells form part of the zebrafish lateral–line system and sense vibration.

Composition of repeating confocal micrographs of a retina from a 30 hours post fertilization double transgenic zebrafish. Multipotent progenitors are shown in magenta, and committed cells are in green.

Width of eye is 200 micrometres.

Retina development, composition

Light microscope image of a normal two-day-old
zebrafish embryo which has been stained to show
all of the nerve cell processes in the eyes and
brain. The embryo is transparent, so the long,
thin processes (axons) can be seen as they leave
the eye and cross the midline of the brain as a
tight bundle, or commissure toward their target
brain regions. (credit: R. MacDonald & S. Wilson)

Two zebrafish embryos at 3-4 days of development.
The one on the bottom is the wild-type showing
normal eye development. The one above has been
injected with 'Sonic hedgehog' (Shh) RNA, a
molecule which, when overexpressed, disrupts
normal signalling in the developing forebrain.
This results in greatly reduced eye development.
(See also B0001092C)

Zebrafish embryos

Lateral view of the head of a one-day zebrafish
embryo which has been labelled with anti-tubulin
antibody to show the neurons and axon pathways.

Transverse section through the brain of a
developing zebrafish embryo.

Zebrafish development

A two day-old twin zebrafish embryo with one shared yolk and tail but two fully developed heads touching each other at the nose.

Transverse section through the head of a zebrafish
embryo which has been stained with an antibody to
Pax6 protein to show normal early brain and eye
development. The widespread distribution of this
protein can be seen in the developing eyes on
either side of the forebrain in the midline.

Credit: R. MacDonald & S. Wilson

Sensory neuromast cells of the zebrafish lateral line and ear detect vibrations in the water. The brain of a transgenic 4 day old zebrafish embryo is seen here as viewed from a lateral aspect (side-view). In addition to the neuromasts (green spots around periphery of fish), neurons in the retina, habenula (brain region responsible for experience-based fear responses) and optic tectum (the visual centre of the brain) also express green fluorescent protein (GFP).

Neuronal tracts and axons have been labelled using antibodies against tubulin (red), a component of the cytoskeleton which supports cell shape. Tiny cilia (hair-like structures) also labelled with tubulin can be seen supporting the sensory neuromast cells.

Width of image is 500 micrometres.

Zebrafish sensory neuromasts

Light microscope image of a normal two-day-old
zebrafish embryo which has been stained to show
the optic nerve axons from the two eyes at the
optic chiasm. This is the point where they cross
the midline of the brain as a tight bundle or
commissure toward their target brain regions.

Credit: R. MacDonald and S. Wilson

A dorsal view of a 3 days post fertilisation Tg(Dlx4/6:GFP) embryo. The embryo has been has been labelled with anti GFP(green) and anti-acetylated tubulin antibody(red) that labels neuronal tracts. This transgenic line expresses GFP in many dopaminergic and GABAergic cells within the brain. Here we can see beautiful expression in the optic tectum, cerebellum, epithalamus and telencephalon.

Despite our apparent perfect bilateral symmetric body plan, we all show small but conspicuous left-right asymmetries that are thought to be evolutionarily advantageous. Brain lateralisation, for instance, leads to an increase in cognitive performance. 

Zebrafish are particularly useful models to study how left-right brain asymmetries arise during embryonic development and how the resultant asymmetric neuronal circuitry ultimately impacts on function and behaviour. 


This figure is a monochrome composite of a confocal micrograph showing the dorsal view of the forebrain of a wild-type zebrafish embryo at 4 days post-fertilization. Wild-type specimens display noticeable neuroanatomical asymmetries of the habenular nuclei in the forebrain, which can be visualised with the help of antibodies labelling different structures. Here the arrangement of the axons, synaptic neuropil and a subtype of habenular neurons are predominantly enriched in the left side of the brain. 



Width of image is approximately 275 micrometres.

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Zebrafish optic chiasm

Zebrafish eye development

Zebrafish eye development

Zebrafish optic chiasm

Zebrafish eye development

Zebrafish eye development

Eye development, zebrafish

Zebrafish embryo

Zebrafish posterior lateral line development

Transverse section of brain and eyes, Zebrafish model

Zebrafish embryo

Retina development, composition

Zebrafish optic chiasm

Zebrafish embryos

Zebrafish eye development

Zebrafish development

A two day-old twin zebrafish embryo with one shared yolk and tail but two fully developed heads touching each other at the nose.

Zebrafish eye development

Zebrafish sensory neuromasts

Zebrafish optic chiasm

Zebrafish eye development

Zebrafish embryo

Dorsal view of the forebrain of a wild-type zebrafish embryo

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Wellcome collection

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Wellcome uses cookies.

Zebrafish optic chiasm

Zebrafish eye development

Zebrafish eye development

Zebrafish optic chiasm

Zebrafish eye development

Zebrafish eye development

Eye development, zebrafish

Zebrafish embryo

Zebrafish posterior lateral line development

Transverse section of brain and eyes, Zebrafish model

Zebrafish embryo

Retina development, composition

Zebrafish optic chiasm

Zebrafish embryos

Zebrafish eye development

Zebrafish development

A two day-old twin zebrafish embryo with one shared yolk and tail but two fully developed heads touching each other at the nose.

Zebrafish eye development

Zebrafish sensory neuromasts

Zebrafish optic chiasm

Zebrafish eye development

Zebrafish embryo

Dorsal view of the forebrain of a wild-type zebrafish embryo

Stay in the know

Wellcome collectionWellcome Collection

Finding us:

Opening times:

Today's opening times

Wellcome collection