|
Inner Nuclear Layer
The inner nuclear layer or layer of inner granules, of the retina, is made up of a number of closely packed cells, of which there are three varieties, viz.: bipolar cells, horizontal cells, and amacrine cells. Bipolar cells The bipolar cells, by far the most numerous, are round or oval in shape, and each is prolonged into an inner and an outer process. They are divisible into rod bipolars and cone bipolars. * The inner processes of the rod bipolars run through the inner plexiform layer and arborize around the bodies of the cells of the ganglionic layer; their outer processes end in the outer plexiform layer in tufts of fibrils around the button-like ends of the inner processes of the rod granules. * The inner processes of the cone bipolars ramify in the inner plexiform layer in contact with the dendrites of the ganglionic cells. Connection types Midget bipolars are linked to one cone while diffuse bipolars take groups of receptors. Diffuse bipolars can take signals from up to 5 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retina
The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then processes that image within the retina and sends nerve impulses along the optic nerve to the visual cortex to create visual perception. The retina serves a function which is in many ways analogous to that of the film or image sensor in a camera. The neural retina consists of several layers of neurons interconnected by synapses and is supported by an outer layer of pigmented epithelial cells. The primary light-sensing cells in the retina are the photoreceptor cells, which are of two types: rods and cones. Rods function mainly in dim light and provide monochromatic vision. Cones function in well-lit conditions and are responsible for the perception of colour through the use of a range of opsins, as well as high-acuity vision used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bipolar Cell Of The Retina
As a part of the retina, bipolar cells exist between photoreceptors (rod cells and cone cells) and ganglion cells. They act, directly or indirectly, to transmit signals from the photoreceptors to the ganglion cells. Structure Bipolar cells are so-named as they have a central body from which two sets of processes arise. They can synapse with either rods or cones (rod/cone mixed input BCs have been found in teleost fish but not mammals), and they also accept synapses from horizontal cells. The bipolar cells then transmit the signals from the photoreceptors or the horizontal cells, and pass it on to the ganglion cells directly or indirectly (via amacrine cells). Unlike most neurons, bipolar cells communicate via graded potentials, rather than action potentials. Function Bipolar cells receive synaptic input from either rods or cones, or both rods and cones, though they are generally designated rod bipolar or cone bipolar cells. There are roughly 10 distinct forms of cone bipolar ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rod Bipolars
Rod, Ror, Ród, Rőd, Rød, Röd, ROD, or R.O.D. may refer to: Devices * Birch rod, made out of twigs from birch or other trees for corporal punishment * Ceremonial rod, used to indicate a position of authority * Connecting rod, main, coupling, or side rod, in a reciprocating engine * Control rod, used to control the rate of fission in a nuclear reactor * Divining rod, two rods believed by some to find water in a practice known as dowsing * Fishing rod, a tool used to catch fish, like a long pole with a hook on the end * Lightning rod, a conductor on top of a building to protect the building in the event of lightning by taking the charge harmlessly to earth * Measuring rod, a kind of ruler * Switch (corporal punishment), a piece of wood as used as a staff or for corporal punishment, or a bundle of such switches * Truss rod, a steel part inside a guitar neck used for its tension adjustment Arts and entertainment * ''Read or Die'', a Japanese anime and manga ** ''Read or Die'' ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inner Plexiform Layer
The inner plexiform layer is an area of the retina that is made up of a dense reticulum of fibrils formed by interlaced dendrites of retinal ganglion cells and cells of the inner nuclear layer The inner nuclear layer or layer of inner granules, of the retina, is made up of a number of closely packed cells, of which there are three varieties, viz.: bipolar cells, horizontal cells, and amacrine cells. Bipolar cells The bipolar cells, by .... Within this reticulum a few branched spongioblasts are sometimes embedded. References External links Overviewat utah.edu * Human eye anatomy {{eye-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ganglionic Layer
The ganglion cell layer (ganglionic layer) is a layer of the retina that consists of retinal ganglion cells and displaced amacrine cells. The cells are somewhat flask-shaped; the rounded internal surface of each resting on the stratum opticum, and sending off an axon which is prolonged into it. From the opposite end numerous dendrites extend into the inner plexiform layer, where they branch and form flattened arborizations at different levels. The ganglion cells vary much in size, and the dendrites of the smaller ones as a rule arborize in the inner plexiform layer as soon as they enter it; while those of the larger cells ramify close to the inner nuclear layer The inner nuclear layer or layer of inner granules, of the retina, is made up of a number of closely packed cells, of which there are three varieties, viz.: bipolar cells, horizontal cells, and amacrine cells. Bipolar cells The bipolar cells, by .... References External links * Human eye anatomy {{eye- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cone Bipolars
A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the apex or vertex. A cone is formed by a set of line segments, half-lines, or lines connecting a common point, the apex, to all of the points on a base that is in a plane that does not contain the apex. Depending on the author, the base may be restricted to be a circle, any one-dimensional quadratic form in the plane, any closed one-dimensional figure, or any of the above plus all the enclosed points. If the enclosed points are included in the base, the cone is a solid object; otherwise it is a two-dimensional object in three-dimensional space. In the case of a solid object, the boundary formed by these lines or partial lines is called the ''lateral surface''; if the lateral surface is unbounded, it is a conical surface. In the case of line segments, the cone does not extend beyond the base, while in the case of half-lines, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encyclopædia Britannica 2006 Ultimate Reference Suite DVD
An encyclopedia (American English) or encyclopædia (British English) is a reference work or compendium providing summaries of knowledge either general or special to a particular field or discipline. Encyclopedias are divided into articles or entries that are arranged alphabetically by article name or by thematic categories, or else are hyperlinked and searchable. Encyclopedia entries are longer and more detailed than those in most dictionaries. Generally speaking, encyclopedia articles focus on ''factual information'' concerning the subject named in the article's title; this is unlike dictionary entries, which focus on linguistic information about words, such as their etymology, meaning, pronunciation, use, and grammatical forms.Béjoint, Henri (2000)''Modern Lexicography'', pp. 30–31. Oxford University Press. Encyclopedias have existed for around 2,000 years and have evolved considerably during that time as regards language (written in a major international or a verna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horizontal Cell
Horizontal cells are the laterally interconnecting neurons having cell bodies in the inner nuclear layer of the retina of vertebrate eyes. They help integrate and regulate the input from multiple photoreceptor cells. Among their functions, horizontal cells are believed to be responsible for increasing contrast via lateral inhibition and adapting both to bright and dim light conditions. Horizontal cells provide inhibitory feedback to rod and cone photoreceptors. They are thought to be important for the antagonistic center-surround property of the receptive fields of many types of retinal ganglion cells. Other retinal neurons include photoreceptor cells, bipolar cells, amacrine cells, and retinal ganglion cells. Structure Depending on the species, there are typically one or two classes of horizontal cells, with a third type sometimes proposed. Horizontal cells span across photoreceptors and summate inputs before synapsing onto photoreceptor cells. Horizontal cells may also syn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amacrine Cell
Amacrine cells are interneurons in the retina. They are named from the Greek roots ''a–'' ("non"), ''makr–'' ("long") and ''in–'' ("fiber"), because of their short neuronal processes. Amacrine cells are inhibitory neurons, and they project their dendritic arbors onto the inner plexiform layer (IPL), they interact with retinal ganglion cells and/or bipolar cells. Structure Amacrine cells operate at inner plexiform layer (IPL), the second synaptic retinal layer where bipolar cells and retinal ganglion cells form synapses. There are at least 33 different subtypes of amacrine cells based just on their dendrite morphology and stratification. Like horizontal cells, amacrine cells work laterally, but whereas horizontal cells are connected to the output of rod and cone cells, amacrine cells affect the output from bipolar cells, and are often more specialized. Each type of amacrine cell releases one or several neurotransmitters where it connects with other cells. They are o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
