Biology 3338A Lecture Notes - Lecture 12: Paraxial Mesoderm, Lateral Plate Mesoderm, Intermediate Mesoderm
16 Jun 2016
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Document Summary
= the process of segmentation of the paraxial mesoderm to form somites, beginning cranially and extending caudally. Its components are (1) periodicity, (2) fissure formation (to separate somites), (3) epithelialization, (4) specification, and (5) differentiation. Notochord is below neural tube (ventral to neural tube) Next to neural tube are structures that form segments. Somite= segmental block of ball of mesoderm formed from paraxial mesoderm adjacent to notochord (axial mesoderm or chordamesoderm). Form from unsegmented mesoderm (called segmental plate in birds) Differentiates to form the axial skeleton (vertebrae, ribs), all skeletal muscle, and the dorsal dermis (layer below epidermis), tendons, joints and dorsal aortic cells. Play a role in determining the migratory path of neural crest cells and spinal nerve axons (neural crest cells give rise to neurons, melanocytes (skin pigment), cartilage, bone and smooth muscle cells) Different types of mesoderm are induced along the d-v axis. Chordamesoderm notochord, part of intervertebral disc. After the neural tube forms, the notochord disappears.
