Embryonic Development

Organogenesis Overview

• Endoderm derives structures including the gastrointestinal tract, liver, pancreas, and respiratory system.
• The primitive streak marks the beginning of gastrulation, establishing the body's axial structure and facilitating cellular migration for organ formation.

Germ Layers and Their Roles

• The placenta is primarily formed from the trophoblast layer, which is derived from the outer cell mass of the blastocyst.
• Neural tube formation occurs through a process called neurulation, where the neural plate folds and fuses to create the tube that becomes the central nervous system.
• The mesoderm gives rise to structures including muscles, bones, and the circulatory system.

Key Processes in Organogenesis

• Embryonic folding occurs laterally and in the cephalocaudal direction, allowing the embryo to assume a more cylindrical shape necessary for development.
• The sacrococcygeal region is associated with body cavities and blood islands, crucial for early blood cell formation and circulation.

Ectoderm Contributions

• The ectoderm is responsible for forming the epidermis, nervous system, and sensory organs during organogenesis.
• Structures NOT derived from the mesoderm include the epidermis and neural tissues, which originate from the ectoderm.

Essential Germ Layers

• The liver develops from the endoderm as part of the foregut during organogenesis, highlighting its critical role in digestive system formation.

Test your knowledge on organogenesis during weeks 3-8 of development with this quiz! Learn about the key germ layers formed from gastrulation, the structures derived from these layers, the role of the primitive streak and notochord, the process of neurulation, lateral body and cephalocaudal folding, and the development of the lateral mesoderm. Challenge yourself and expand your understanding of embryonic development!