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

Recent Examples on the Web

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

Word History

Etymology

translation of German Primitivstreifen

First Known Use

1833, in the meaning defined above

Medical Definition

primitive streak

noun

: an elongated band of cells that forms along the axis of an embryo early in gastrulation by the movement of lateral cells toward the axis and that develops a groove along its midline through which cells move to the interior of the embryo to form the mesoderm