primitive streak
noun
: an elongated band of cells that forms along the axis of a developing fertilized egg early in gastrulation and that is considered a forerunner of the neural tube and nervous system
Examples of primitive streak in a Sentence
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The primitive streak—a developmental precursor of the spine—shows up.
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Kristen V. Brown, The Atlantic, 8 Oct. 2024
Lewis Wolpert In 1990, following reports from the U.S. Department of Health, Education and Welfare and the U.K. Warnock Committee years earlier, many countries decided that the formation of the primitive streak at 14 days should mark the limit for how long human embryos could be sustained in vitro.
—Philip Ball, Quanta Magazine, 13 June 2023
Laws limiting embryo research to either 14 days or formation of a structure called the primitive streak exist in several countries, including the United Kingdom, Sweden, and South Korea.
—Kelly Servick, Science | AAAS, 26 May 2021
In that transition, the embryo forms a furrow called the primitive streak and folds inward on itself while cells mature into different lineages that will later give rise to all the organs and tissues of the body.
—Kelly Servick, Science | AAAS, 23 May 2018
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Kristen V. Brown, The Atlantic, 8 Oct. 2024
Lewis Wolpert In 1990, following reports from the U.S. Department of Health, Education and Welfare and the U.K. Warnock Committee years earlier, many countries decided that the formation of the primitive streak at 14 days should mark the limit for how long human embryos could be sustained in vitro.
—Philip Ball, Quanta Magazine, 13 June 2023
Laws limiting embryo research to either 14 days or formation of a structure called the primitive streak exist in several countries, including the United Kingdom, Sweden, and South Korea.
—Kelly Servick, Science | AAAS, 26 May 2021
In that transition, the embryo forms a furrow called the primitive streak and folds inward on itself while cells mature into different lineages that will later give rise to all the organs and tissues of the body.
—Kelly Servick, Science | AAAS, 23 May 2018
Cite this Entry
“Primitive streak.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/primitive%20streak. Accessed 15 Jul. 2025.
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