BIOL 1082 Lecture Notes - Lecture 26: Zona Pellucida, Amniotic Sac, Neural Crest
Gastrulation
Embryogenesis
• Cleavage- splitting without growth
• Zona pellucida- thick outer membrane surrounding ovum before implantation
• Compaction- cells get closer together
• Differentiation- being able to tell cells apart
• Trophoblast- cells on outside
• Cavity- blastocoel
• Entire thing- trophoblast, blastocoel, inner cell mass= blastocyst
• Amniotic cavity develops
Gastrulation
• Formation of the three layers
• Invagination through primitive groove
• Ectoderm
• Mesoderm-bone, muscle, pleura, parietal lining of body cavity, urogenital organs, CT
• Endoderm –lining of internal organs, GI tract, airways---notochord (induces neurulation)
Neurulation
• Final stage
• Mesoderm- further differentiation of cells; cord formed
• Thickening of ectoderm
• Invagination of ectoderm to become neural tube
• Neural crest cells
• Somites
• Neural tube becomes CNS
Organogenesis
• Process by which the 3 germ layers form many of the organs and structures found in the
adult individual
• Ectoderm
• Mesoderm- bone is a type of CT
• Endoderm
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