![]() ![]() Myelin Sheath: multilayered wrapping of cell membrane around an axon. Internode: each myelinated segment (of an axon). (Goldberg, 40-41) Begins at the “axon hillock” and stops at the “axon terminal.” (Characterized by) discontinuous segments. The brain structures are not fully functional until the axons connecting them are insulated with myelin, and the time course of myelination varies vastly from structure to structure. Myelination: the process by which “glial” cells wrap around long axons, forming a fatty protective coating called “myelin.” The dramatic increase in brain weight during the first years of life is largely due to myelination. Newborn stem cells need to move away from their “precursors” before (the precursors) can “differentiate.” (Best of the Brain-Fred Gage, 123) ![]() (Brooker, 203) Only 50% on average migrate successfully, the others perish. (Kolb, 195-196) During “embryonic development” in animals, cells migrate to their appropriate positions within the body. Begins about 8 weeks after “conception” and is largely complete by about 29 weeks. (Kolb, 198) Verb - ‘arborize.’Ĭell Migration: (process of) newly formed cells traveling to their correct location. Arborization: a process of early growth of “dendrites.” (Goldberg, 39) Dendrites begin as individual "processes" protruding from the "cell body." Later, they develop increasingly complex extensions that look much like the branches of trees visible in winter. ![]()
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