Germ layer

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Germ layer is a primary layer of cells that form during embryogenesis. The three germ layers in vertebrates are particularly among the most fundamental topics in embryology. These layers are the ectoderm, mesoderm, and endoderm.

Overview[edit | edit source]

Germ layers start to form after the fertilization of an egg by a sperm cell. Once the zygote divides, it becomes a blastula, which is a hollow ball of cells. The blastula undergoes gastrulation, forming the three germ layers: ectoderm, mesoderm, and endoderm.

Ectoderm[edit | edit source]

The ectoderm forms the outermost layer and gives rise to the central nervous system, the peripheral nervous system, and the epidermis with its associated structures including hair and nails.

Mesoderm[edit | edit source]

The mesoderm forms the middle layer and gives rise to the muscles, the circulatory and excretory systems, the reproductive system, dermis and other connective tissues of the body.

Endoderm[edit | edit source]

The endoderm forms the innermost layer and gives rise to the lining of the digestive tract and its associated structures, the respiratory system, the urinary bladder, and the digestive organs.

See also[edit | edit source]

References[edit | edit source]


External links[edit | edit source]

Germ layer Resources
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Contributors: Prab R. Tumpati, MD