A Golgi impregnated neuron has been placed on top. Rat cerebral cortex after general staining. Neuron of rat cerebral cortex after the Golgi's staining. The size and shape of the soma, the branching pattern and density of dendrites, as well as the length and branching of the axon are different for each type of neuron type.įigure 2. A neuron is divided in three domains: soma, dendrite and axon (Figures 2 and 3). Neurons show the most complex and diverse cellular morphology of the body. Image from the cerebral cortex and hippocampus of the a rat brain. In humans, the majority of neurons are found in the cerebellum, nearly 70000 millions, and in the cerebral cortex with around 15000 millions.įigure 1. In the mouse encephalon, the total number of neurons is around 71 millions (reviewed in Heculano-Houzel 2009 see Figure 1). There are more in the spinal cord and in the peripheral nervous system. The estimated total number of neurons in the human encephalon is around 86000 millions. In the central nervous system there are numerous neuronal circuits that connected between each other. Some specialized neurons communicate with muscle cells by complex synapses known as motor plates. Neurons communicate with each other through specialized structures called synapses, which allow the formation of such circuits. Neurons are specialized in the reception, processing and sending information by chemical and electrical mechanisms that are fundamentally associated to their plasma membranes.Īll these functions are carried out by ensembles of neurons connected with one another forming complex neuronal circuits. The nervous system allows animals to communicate with the external environment and internal environments by sensing a broad variety of stimuli, processing the information, and sending orders, usually a muscle contraction that moves some parts of the organism or the whole body. Neurons, together with glial cells, are the cells that form the central and peripheral nervous systems. The pseudounipolar neurons in the mesencephalic nucleus carry proprioceptive information from the muscle of mastication.Cell types. Some of the pseudounipolar neurons in the inferior ganglion of the glossopharyngeal nerve carry information from the carotid body and carotid sinus. Pseudounipolar neurons in the geniculate ganglion, inferior ganglion of the glossopharyngeal nerve and inferior ganglion of the vagus nerve also carry information about taste from taste buds. The ones found in the dorsal root ganglia, and majority of those in cranial nerve sensory ganglia carry information about touch, vibration, proprioception, pain and temperature. It is the only location in the central nervous system where the cell bodies of pseudounipolar neurons are found.Īll pseudounipolar neurons are sensory neurons. The mesencephalic nucleus is made up of pseudounipolar neurons which migrated into the brainstem during embryological development. While the vestibulocochlear nerve has two ganglia associated with it ( spiral ganglion and vestibular ganglion), both contain bipolar neurons, not pseudounipolar. Pseudounipolar neurons in cranial nerve sensory ganglia synapse in the main sensory trigeminal nucleus, spinal trigeminal nucleus or solitary nucleus.
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