Search results
Results from the WOW.Com Content Network
Substances exchanged include small molecules, substrates, and metabolites. [1] Gap junctions were first described as close appositions as other tight junctions, but following electron microscopy studies in 1967, they were renamed gap junctions to distinguish them from tight junctions. [2] They bridge a 2-4 nm gap between cell membranes. [3]
Each gap junction (sometimes called a nexus) contains numerous gap junction channels that cross the plasma membranes of both cells. [11] With a lumen diameter of about 1.2 to 2.0 nm, [2] [12] the pore of a gap junction channel is wide enough to allow ions and even medium-size molecules like signaling molecules to flow from one cell to the next, [2] [13] thereby connecting the two cells' cytoplasm.
Interkinetic nuclear migration is a feature of developing neuroepithelia and is characterized by the periodic movement of the cell’s nucleus with the progression of the cell cycle. Developing neuroepithelia are tissues composed of neural progenitor cells, each spanning the entire thickness of the epithelium from the ventricular surface to the ...
At a chemical synapse, one neuron releases neurotransmitter molecules into a small space (the synaptic cleft) that is adjacent to another neuron. The neurotransmitters are contained within small sacs called synaptic vesicles, and are released into the synaptic cleft by exocytosis.
Neurons vary in shape and size and can be classified by their morphology and function. [20] The anatomist Camillo Golgi grouped neurons into two types; type I with long axons used to move signals over long distances and type II with short axons, which can often be confused with dendrites. Type I cells can be further classified by the location ...
[z] Neurotransmitters are small molecules that may open ion channels in the postsynaptic cell; most axons have the same neurotransmitter at all of their termini. The arrival of the action potential opens voltage-sensitive calcium channels in the presynaptic membrane; the influx of calcium causes vesicles filled with neurotransmitter to migrate ...
In both images neurons are stained with a somatodendritic marker, microtubule associated protein (red). In the right image, synaptic vesicles are stained in green (yellow where the green and red overlap). Scale bar = 25 μm. [3] Synaptic vesicles are relatively simple because only a limited number of proteins fit into a sphere of 40 nm diameter.
In the developing zebrafish spinal cord, early spontaneous activity is required for the formation of increasingly synchronous alternating bursts between ipsilateral and contralateral regions of the spinal cord and for the integration of new cells into the circuit. [63] Motor neurons innervating the same twitch muscle fibers are thought to ...