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The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles [1] and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell and contained within the nuclear membrane is termed the nucleoplasm .
Drawing of Purkinje cells (A) and granule cells (B) from pigeon cerebellum by Santiago Ramón y Cajal, 1899.Instituto Santiago Ramón y Cajal, Madrid, Spain. The name granule cell has been used for a number of different types of neurons whose only common feature is that they all have very small cell bodies.
Brain cells make up the functional tissue of the brain. The rest of the brain tissue is the structural stroma that includes connective tissue such as the meninges, blood vessels, and ducts. The two main types of cells in the brain are neurons, also known as nerve cells, and glial cells, also known as neuroglia. [1]
Tau proteins are found more often in neurons than in non-neuronal cells in humans. One of tau's main functions is to modulate the stability of axonal microtubules. [11] [13] Other nervous system microtubule-associated proteins (MAPs) may perform similar functions, as suggested by tau knockout mice that did not show abnormalities in brain development – possibly because of compensation in tau ...
The proportion of astrocytes in the brain is not well defined; depending on the counting technique used, studies have found that the astrocyte proportion varies by region and ranges from 20% to around 40% of all glia. [3] Another study reports that astrocytes are the most numerous cell type in the brain. [2]
Pyramidal cells are among the largest neurons in the brain. Both in humans and rodents, pyramidal cell bodies (somas) average around 20 μm in length. Pyramidal dendrites typically range in diameter from half a micrometer to several micrometers. The length of a single dendrite is usually several hundred micrometers.
Purkinje-specific gene markers were also proposed by comparing the transcriptome of Purkinje-deficient mice with that of wild-type mice. [10] One illustrative example is the Purkinje cell protein 4 ( PCP4 ) in knockout mice , which exhibit impaired locomotor learning and markedly altered synaptic plasticity in Purkinje neurons.
Plasma cells can only produce a single kind of antibody in a single class of immunoglobulin. In other words, every B cell is specific to a single antigen, but each cell can produce several thousand matching antibodies per second. [14] This prolific production of antibodies is an integral part of the humoral immune response. [citation needed]