Question

Why is gastrulation considered a dynamic event in embryonic development? Describe the formation of three germ layers. Name one part formed by each layer.

Answer 1

Gastrulation occurs after fertilization of an egg cell by a sperm cell. It's one of the processes that readies an organism for more complex processes. Gastrulation is followed by organogenesis, when individual organs develop within the newly formed germ layers.Each layer gives rise to specific tissues and organs in the developing embryo.

Gastrulation rearranges the cells of the blastula and ultimately forms the three germ layers of the embryo. The primary layers that will form all of the major body and organ systems of the organism, these germ layers include the ectoderm, mesoderm, and endoderm. They are the outer, middle, and inner layers, respectively.

The ectoderm gives rise to epidermis, the nervous system, and to the neural crest in vertebrates. The endoderm gives rise to the epithelium of the digestive system and respiratory system, and organs associated with the digestive system, such as the liver and pancreas. The mesoderm gives rise to many cell types such as muscle, bone, and connective tissue.

In vertebrates, mesoderm derivatives include the notochord, the heart, blood and blood vessels, the cartilage of the ribs and vertebrae, and the dermis. Following gastrulation, cells in the body are either organized into sheets of connected cells (as in epithelia), or as a mesh of isolated cells, such as mesenchyme.