Dictionary » R » Retina



light sensitive layer of the eye. In vertebrates, looking from outside, there are four major cell layers: (i) the outer neural retina, which contains neurons (ganglion cells, amacrine cells, bipolar cells) as well as blood vessels, (ii) the photoreceptor layer, a single layer of rods and cones, (iii) the pigmented retinal epithelium (PRE or RPE), (iv) the choroid, composed of connective tissue, fibroblasts and including a well vascularised layer, the chorio capillaris, underlying the basal lamina of the PRE. Behind the choroid is the sclera, a thick organ capsule.

In molluscs (especially cephalopods such as the squid) the retina has the light sensitive cells as the outer layer with the neural and supporting tissues below.

See: retinal rods, retinal cones, rhodopsin. The light-sensitive membrane covering the back wall of the eyeball; it is continuous with the optic nerve.The interior lining of the vertebrate eye that contains photoreceptors cells (sensitive to light) in the form of 'rods' and 'cones' that can distinguish the various colours in light.

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Extra Light For Compound Light Microscope ???

... uses visible light for illuminating the object . it contains glass lenses that magnify the image of the object and focus the light on the retina of the observer's eye . it has two lenses one at each end of a hollow tube.The lens closer to the object being viewed is called objective lens.the ...

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by Kehsibashok
Sun Jul 28, 2013 6:12 am
Forum: Cell Biology
Topic: Extra Light For Compound Light Microscope ???
Replies: 1
Views: 2048

Re: About how many megapixels would human eye hold?

"The average human retina has five million cone receptors on it. Since the cones are responsible for color vision, you might suppose that this equates to a five megapixel equivalent for the human eye. But there are also a hundred ...

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by hymenoptera7
Tue Jun 25, 2013 2:42 am
Forum: General Discussion
Topic: About how many megapixels would human eye hold?
Replies: 1
Views: 1617

Knockout mice

I ran across a paper with the genetic version of knockdown mice this morning. "Knockdown of Cdc42 in the developing retina was achieved by crossing Cdc42 floxed mice [29] with mice expressing cre recombinase under the control of the α element of the Pax6 promoter [30]. " ...

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by jonmoulton
Wed Feb 06, 2013 4:24 pm
Forum: Genetics
Topic: Knockout mice
Replies: 5
Views: 5622

What are some reasons that prove adaptations are not designe

... through the nerve cells before striking the rods and cones. Also, those nerves have to leave the eye via the optic nerve, which passes through the retina, leaving a blind spot in each eye. The tissue from which cephalopod eyes is derived is the skin. So, the light sensitive cells are already on ...

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by thoffnagle
Thu Jan 31, 2013 1:04 am
Forum: Evolution
Topic: What are some reasons that prove adaptations are not designe
Replies: 12
Views: 8489

Females heterozygous for X linked diseases

... one X chromosome in somatic cells.So, if a human female was daltonism carrier, would not she be half daltonic?Because, ~1/2 of her cells in retina would have a recessive allele and the other half would have the dominant allele?Or 1/2 is not enough to cause color blindness?And I'd like to ...

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by kysa
Fri Jan 04, 2013 5:04 pm
Forum: Genetics
Topic: Females heterozygous for X linked diseases
Replies: 1
Views: 1694
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