Development of Nervous System PDF
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Jiitima
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Summary
This document provides a detailed overview of the development of the nervous system, starting from the ectoderm thickening and forming the neural plate. It outlines the stages of folding, fusion, and formation of the neural tube, and the development of primary and secondary vesicles. The document also includes a description of the differentiation and proliferation of neuroepithelial cells and the division of sensory and motor neurons.
Full Transcript
18/10/2024 -- Development of Nervous System: Jiitima - Development of nervous system begins at 3^rd^ week when area of ectoderm (outer tissue layer of embryo) thickens and forms neural plate. - Neural plate folds inwards forming groove called neural groove - Sides of neural groove (...
18/10/2024 -- Development of Nervous System: Jiitima - Development of nervous system begins at 3^rd^ week when area of ectoderm (outer tissue layer of embryo) thickens and forms neural plate. - Neural plate folds inwards forming groove called neural groove - Sides of neural groove (aka neural folds) start to come together; end of 3^rd^ week folds will begin to fuse together - End of 4^th^ week, completely fused together to form neural tube (will become brain and spinal cord) - As neural tube closes, bulges and bends begin to appear and become more noticeable - During 4^th^ week, 3 bulges present (primary vesicles) - 1 -- Prosencephalon (forms cerebrum), 2- mesencephalon (forms midbrain), 3 - rhombencephalon (forms rest of brainstem and cerebellum) - End of neural tube forms spinal cord A diagram of a mesencephalon Description automatically generated - As brain continues to develop, 2 of the vesicles further subdivide to form secondary vesicles (prosencephalon forms telencephalon \[becomes cerebral hemisphere\] and diencephalon \[becomes thalamus, hypothalamus and other structures\], mesencephalon does not subdivide and becomes midbrain, rhombencephalon subdivide into metencephalon (becomes pons and cerebellum) and myelencephalon (becomes medulla)  - Neural tube will continue to develop to look more like the brain (telencephalon will grow more rapidly than other parts) A cartoon of a green mask Description automatically generated with medium confidence Development of spinal cord and brainstem: - Neuroepithelial cells that make up the neural tube differentiate and proliferate - Migrate from more central region near neural canal and push outwards as daughters cells come into existence and need more space, push more laterally and form an intermediate zone and finally a marginal zone - Marginal zone meets the sclerotomal mesenchyme (is superficial to the marginal zone), becomes the meninges - Intermediate zone and marginal zone quickly fill space inside neural canal and differentiate into actual neurons - Neural canal will become central canal. Central canal of neural tube lined with ependymal cells derived from neural tube Division of sensory and motor neurons: - Neuroepithelial cells take on different roles depending upon position relative to a dividing line (sulcus limitans) 
