The word "ectoderm" refers to the outermost layer of cells in embryonic development, which gives rise to the skin and nervous system. It is pronounced as /ˈɛktəˌdɜrm/ with four syllables: "EK-tuh-durm". The phonetic transcription shows that the first syllable is stressed and pronounced with the short "e" sound, followed by the "k" sound. The second syllable is pronounced with the schwa sound, represented by the upside-down "e" symbol, followed by the "t" sound. The third and fourth syllables are pronounced with the vowel "er" and the consonant "m", respectively.
The term "ectoderm" refers to one of the three primary germ layers in the early development of multicellular organisms, especially animals. It is the outermost layer of cells in the embryo, which gives rise to various structures and tissues in the organism. The ectoderm is crucial in forming the skin, hair, nails, glands, and the nervous system, including the brain and spinal cord.
During embryogenesis, the ectoderm originates from the outermost layer of the blastula, a hollow sphere of cells formed during early embryonic development. As the embryo continues to grow, the ectoderm differentiates into distinct cell types and tissues, thereby contributing to the formation of different organs and systems.
Apart from its role in developing the integumentary and nervous systems, the ectoderm also plays a critical part in other structures. It gives rise to the lens and cornea of the eye, the inner ear, the mammary glands, as well as various glands in the skin, such as sebaceous and sweat glands.
In summary, the ectoderm is the primary germ layer responsible for the outermost layer of cells in the developing embryo. It gives rise to diverse structures, including the skin, nervous system, eyes, ears, and various glands. The ectoderm is vital for the overall development and organization of multicellular organisms.
The outer layer of cells formed from the inner cell-mass in the blastocyst.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
The word "ectoderm" is derived from the Greek words "ektos", meaning "outside", and "derma", meaning "skin". In embryology, ectoderm refers to the outermost layer of cells in a developing embryo that gives rise to structures such as the nervous system, skin, and sensory organs.