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Myelin is formed by oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system.Therefore, the first stage of myelinogenesis is often defined as the differentiation of oligodendrocyte progenitor cells (OPCs) or Schwann cell progenitors into their mature counterparts, [4] followed by myelin formation around axons.
Myelin (/ ˈ m aɪ. ə l ɪ n / MY-ə-lin) is a lipid-rich material that surrounds nerve cell axons to insulate them and increase the rate at which electrical impulses (called action potentials) pass along the axon. [1] [2] The myelinated axon can be likened to an electrical wire (the axon) with insulating material (myelin) around it. However ...
End of life – life is the characteristic distinguishing physical entities having signaling and self-sustaining processes from those that do not, [1] [2] either because such functions have ceased , or because they lack such functions and are classified as inanimate. [3] [4] [5] (Death is) the opposite of: Life – (see above)
Beginning in the future neck region, the neural folds of this groove close to create the neural tube. The formation of the neural tube from the ectoderm is called neurulation. The ventral part of the neural tube is called the basal plate; the dorsal part is called the alar plate. The hollow interior is called the neural canal. By the end of the ...
The remainder of the ectoderm gives rise to the epidermis. The ability of the mesoderm to convert the overlying ectoderm into neural tissue is called neural induction. In the early embryo, the neural plate folds outwards to form the neural groove. Beginning in the future neck region, the neural folds of this groove close to create the neural tube.
The first English use of the expression "meaning of life" appears in Thomas Carlyle's Sartor Resartus (1833–1834), book II chapter IX, "The Everlasting Yea". [1]Our Life is compassed round with Necessity; yet is the meaning of Life itself no other than Freedom, than Voluntary Force: thus have we a warfare; in the beginning, especially, a hard-fought battle.
Monty Python's The Meaning of Life, also known simply as The Meaning of Life, is a 1983 British musical sketch comedy film written and performed by the Monty Python troupe, directed by Terry Jones. The Meaning of Life was the last feature film to star all six Python members before the death of Graham Chapman in 1989.
The earliest evidence for life on Earth includes: 3.8 billion-year-old biogenic hematite in a banded iron formation of the Nuvvuagittuq Greenstone Belt in Canada; [30] graphite in 3.7 billion-year-old metasedimentary rocks in western Greenland; [31] and microbial mat fossils in 3.48 billion-year-old sandstone in Western Australia.