Nelson & Connaughton, Bipolar Cell Pathways in the Vertebrate Retina. There are situations where multiple axons arise, but that occurs only in neurons that have been tinkered around with genetically. Basically, the neuron has still just one axonal output, but collateral regulatory info is sent off back to the cell. The only situation where multiple axons arise from one cell is when the axon bifurcates along the way, sending one or more collaterals from the axon off back to the cell. In addition, microtubules in dendrites have their positive ends toward the cell soma. Meaning, Axons are the cytoplasmic projections of the soma that appear as elongated fibres, Dendrites are the cytoplasmic projection of the soma that appear as. The microtubule associated proteins (MAPs) in the dendrite have a higher molecular weight than those found in the axon. bipolar cells), others as many as thousands of terminals (Brady et al., 2012). Dendrites contain numerous orderly arrays of microtubules and fewer neurofilaments (see below). The axon can target neurons along the way ( en passant) and the axon can terminate in multiple terminals contacting various cells. In particular, Cajal made the observation that in many invertebrate neurons and even in some vertebrate neuronal types (such as the crook-shaped cell in the optic lobe of birds), the axon arose from a dendrite, hence compromising the theory of cellulipetal and cellulifugal propagation of information. ![]() Hence, dependent on the cell type, neurons can have one or as many as 200k dendritic connections.Īs far as I am aware, all neurons have just one axon. An individual neuron can be viewed as a mosaic of structur- ally distinct cellular domains-cell body, dendrites, axon. The space between the axon terminal of one cell and the dendrites of the next is called the synapse. The axon terminal has vesicles filled with neurotransmitters ready to be released. Dendrites arise from the receiving surface of the nerve. Within a cell, action potentials are triggered at the cell body, travel down the axon, and end at the axon terminal. ![]() Hence they integrate massive amounts of (sensory) information and funnel it into one output signal (Purves et al., 2002). The molecular profiling of single axons and dendrites in living neurons could provide important information for the better understanding of neuron function. Axon: Dendrites: 1: There is only one axon per neuron: Usually many dendrites per neuron: 2: Axon arises from the discharging end of the nerve. These cells have elaborate dendritic trees making 100,000 to 200,000 connections, but still there is just one axon. Multipolar neurons have multiple inputs (dendritic connections), and one output (the axon).There are also bipolar cells in the retina, these have one dendrite (input) and one axon (output) (Nelson & Connaughton, 2012).Ī striking example are the Purkinje cells in the cortex.
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