BIOL3030 Lecture Notes - Lecture 3: Pigment, Pharyngeal Arch, Dermal Bone
23 Jan 2017
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Neural crest: 4th layer or germ layer. Becomes teeth, valves in heart, melanophores, eyes, organs, neurons. Modify appendicular muscle systems for fins, digestive system, pharynx is used for processing prey instead of filtering. Mouth, perforated pharynx, gut, anus, notochord, dorsal tubular nerve cord. Elaboration of chordate characters in vertebrates: ectoderm. Folding of interior neural tube: formation of sensory placodes. Sensory systems are great for finding food. Placodes: release cells to become ears eyes nose (neural parts) Special senses: placodes: dedicated cranial nerve, own organ so only does that function. Placodes develop in place: sub-organs of brain in placode areas. More specialized in vertebrates: to intervertebral discs. Much more specialized further back: somites to vertebrates. Paraxial mesoderm or somites: vertebrae and axial skeleton. Fin or leg given rise from somites: body segments. Segmental muscles: myomeres: remnants become segmented muscles. Migratory muscle cells: somitic derivatives are segmental. Come off and go to other places: biceps. Occurs between lateral plate and paraxial mesoderm.
