Embryonic Development of the Spinal Cord and Associated Disorders

摘要: The three primary germ cell layers — ectoderm, mesoderm and entoderm are present in the embryonic disc by end of second gestational week. At this time, a single sheet cells (i.e. midline ectoderm) undergoes time-specific induction underlying to become neural plate. During third week, ectodermal plate enlarges is further induced entodermally derived notochord form midaxial groove which sinks deeper. Its edges (neural folds) converge fuse dorsally primitive tube. Fusion commences near midpoint embryo progresses rostrally caudally usually complete fourth early formation tube neurulation now basically complete.