Which germ layer develops first during embryonic development?

The endoderm is one of the germ layers formed during animal embryogenesis. Cells migrating inward along the archenteron form the inner layer of the gastrula, which develops into the endoderm. It is the first layer to be developed.

What are embryonic germ layers?

germ layer, any of three primary cell layers, formed in the earliest stages of embryonic development, consisting of the endoderm (inner layer), the ectoderm (outer layer), and the mesoderm (middle layer).

What are the 3 germ layers and what do they become during development?

Cells in each germ layer differentiate into tissues and embryonic organs. The ectoderm gives rise to the nervous system and the epidermis, among other tissues. The mesoderm gives rise to the muscle cells and connective tissue in the body. The endoderm gives rise to the gut and many internal organs.

What do the endoderm ectoderm and mesoderm form?

During gastrulation, a hollow cluster of cells called a blastula reorganizes into two primary germ layers: an inner layer, called endoderm, and an outer layer, called ectoderm. In all animals, except for organisms of the phylum Cnidaria, the endoderm and ectoderm interact to produce a third germ layer, called mesoderm.

What do ectoderm mesoderm and endoderm develop into?

The ectoderm gives rise to the skin and the nervous system. The mesoderm specifies the development of several cell types such as bone, muscle, and connective tissue. Cells in the endoderm layer become the linings of the digestive and respiratory system, and form organs such as the liver and pancreas.

What is developed from ectoderm?

The ectoderm gives rise to the skin, the brain, the spinal cord, subcortex, cortex and peripheral nerves, pineal gland, pituitary gland, kidney marrow, hair, nails, sweat glands, cornea, teeth, the mucous membrane of the nose, and the lenses of the eye (see Fig. 5.3).

Where is gastrula formed?

The gastrula develops from the hollow, single-layered ball of cells called a blastula which itself is the product of the repeated cell division, or cleavage, of a fertilized egg. This cleavage is followed by a period of development in which the most significant events are movements of cells relative to one another.

What can develop from the endoderm?

Endoderm forms the epithelium—a type of tissue in which the cells are tightly linked together to form sheets—that lines the primitive gut. From this epithelial lining of the primitive gut, organs like the digestive tract, liver, pancreas, and lungs develop.