blas·​to·​cyst | \ ˈbla-stə-ˌsist How to pronounce blastocyst (audio) \

Definition of blastocyst

: the modified blastula of a placental mammal having an outer layer composed of the trophoblast

Examples of blastocyst in a Sentence

Recent Examples on the Web

Leaving embryos undisturbed from day one to day five —when the embryo becomes what’s known as a blastocyst—rather than checking on them on day three, as many centers do, has been similarly revolutionary. Jancee Dunn, Vogue, "How California Became the World’s Fertility Treatment Destination," 13 Mar. 2019 For now, these early embryos, called blastocysts, have been frozen. NBC News, "Scientists use test-tube science to save nearly extinct rhino," 4 July 2018 In mammals, a hollow sphere made out of fewer than 100 cells (called a blastocyst) forms days after an egg is fertilized. Laura Yan, Popular Mechanics, "This Artificial Embryo Actually Started Pregnancy In Mice," 5 May 2018 Water in the blastocysts cells is replaced with a cryoprotectant, which functions like antifreeze. Ginger Christ And Julie Washington,, "Tours of Ohio fertility clinics show procedures in place to safeguard eggs, embryos (photos, videos)," 25 Mar. 2018 Now, using mouse stem cells instead of the usual sperm and egg, scientists have created a structure like a blastocyst -- an early embryo. Susan Scutti, CNN, "Embryo-like structure synthesized in a lab could help decipher infertility," 3 May 2018 Five days after the donor's eggs were harvested and fertilized, one blastocyst was transferred to my uterus. Sarah Kowalski, Harper's BAZAAR, "The Misleading Promise of IVF for Women Over 40," 21 Feb. 2018 Then they are left in a petri dish to grow into what are called blastocysts. Washington Post, "Social egg freezing is a numbers game that many women don't understand," 30 Jan. 2018 Meanwhile my body was prepped to mimic the phase of my cycle optimal for implantation of a blastocyst, or fertilized egg. Sarah Kowalski, Harper's BAZAAR, "The Misleading Promise of IVF for Women Over 40," 21 Feb. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'blastocyst.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of blastocyst

1876, in the meaning defined above

History and Etymology for blastocyst

blasto- + -cyst

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Time Traveler for blastocyst

The first known use of blastocyst was in 1876

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blas·​to·​cyst | \ ˈblas-tə-ˌsist How to pronounce blastocyst (audio) \

Medical Definition of blastocyst

: the modified blastula of a placental mammal

More from Merriam-Webster on blastocyst Encyclopedia article about blastocyst

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