Neurulation and the Formation of Axial Structures Neurulation
Chapter 7: Neurulation and the Formation of Axial Structures
Neurulation The stage of organogenesis in vertebrate embryos, during which the neural tube is transformed into the primitive structures that will later develop into the central nervous system. In development, this starts with the first traces of formation of the neural plate and ends with closure of the neural tube. Induction Process by which the presence of one tissue influences the development of another. Some considerations: Absence of inducing tissue results in the lack or improper development of induced tissue. Addition of extra inducing tissue in an abnormal position results in aberrantly located induced tissue.
Summary of Inductive Interactions
Unspecialized ectoderm cells
Action of chordamesoderm Formation of thickened plate
Formation of groove
Formation of neural tube
Formation of spinal cord and brain
Other inductive events Neural crest (located at the edges of the lateral plates of the folding neural tube) separate from the neural tube and migrate to become a variety of different but important cells. Neural crest cells will migrate through the embryo and will give rise to several cell populations, including pigment cells and the cells of the peripheral nervous system.
Primary (Neural) Induction The reaction which initiates both the formation of the CNS and causes the central longitudinal axis of the body to be established. Occurs shortly after gastrulation. Chordal cells induce overlying ectoderm to form neural plate. Inductor: Chordamesoderm Responding Tissue: Ectoderm Consideration: The inductor and inductee must be at the right place at the right time. The ectoderm must be competent to be induced
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During much of the period of gastrulation in amphibians and birds, both the dorsal and ventral ectoderm has the competence to form the neural tissues when subjected to the influence of inductors. Later in gastrula stage,
Neurulation The stage of organogenesis in vertebrate embryos, during which the neural tube is transformed into the primitive structures that will later develop into the central nervous system. In development, this starts with the first traces of formation of the neural plate and ends with closure of the neural tube. Induction Process by which the presence of one tissue influences the development of another. Some considerations: Absence of inducing tissue results in the lack or improper development of induced tissue. Addition of extra inducing tissue in an abnormal position results in aberrantly located induced tissue.
Summary of Inductive Interactions
Unspecialized ectoderm cells
Action of chordamesoderm Formation of thickened plate
Formation of groove
Formation of neural tube
Formation of spinal cord and brain
Other inductive events Neural crest (located at the edges of the lateral plates of the folding neural tube) separate from the neural tube and migrate to become a variety of different but important cells. Neural crest cells will migrate through the embryo and will give rise to several cell populations, including pigment cells and the cells of the peripheral nervous system.
Primary (Neural) Induction The reaction which initiates both the formation of the CNS and causes the central longitudinal axis of the body to be established. Occurs shortly after gastrulation. Chordal cells induce overlying ectoderm to form neural plate. Inductor: Chordamesoderm Responding Tissue: Ectoderm Consideration: The inductor and inductee must be at the right place at the right time. The ectoderm must be competent to be induced
1|P a g e
During much of the period of gastrulation in amphibians and birds, both the dorsal and ventral ectoderm has the competence to form the neural tissues when subjected to the influence of inductors. Later in gastrula stage,