- published: 28 Feb 2013
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The blastula (from Greek βλαστός (blastos), meaning "sprout") is a hollow sphere of cells formed during an early stage of embryonic development in animals . The blastula is created when the zygote undergoes the cell division process known as cleavage. The blastula is preceded by the morula and is followed by the gastrula in the developmental sequence.[citation needed]
A common feature of a vertebrate blastula is that it consists of a layer of blastomeres, known as the blastoderm, which surrounds an interior central cavity known as the blastocoel. In mammals, blastulation leads to the formation of the blastocyst, which must not be confused with the blastula. The blastocyst contains an embryoblast, which is homologous to the blastula. However, it also includes the trophoblast, which goes on to form the extraembryonic tissues.[citation needed]
Joni Mitchell, CC (born Roberta Joan Anderson; November 7, 1943) is a Canadian musician, singer songwriter, and painter. Mitchell began singing in small nightclubs in Saskatchewan and Western Canada and then busking in the streets and dives of Toronto. In 1965 she moved to the United States and, touring constantly, began to be recognized when her original songs ("Urge for Going," "Chelsea Morning," "Both Sides, Now," "The Circle Game") were covered by notable folk singers, allowing her to sign with Reprise Records and record her own debut album in 1968. Settling in Southern California, Mitchell and her popular songs like "Big Yellow Taxi" and "Woodstock" helped define an era and a generation. Her more starkly personal 1971 recording Blue has been called one of the best albums ever made. Musically restless, Mitchell switched labels and began moving toward jazz rhythms by way of lush pop textures on 1974's Court and Spark, her best-selling LP, featuring her radio hits "Help Me" and "Free Man in Paris."
Patricia Lee "Patti" Smith (born December 30, 1946) is an American singer-songwriter, poet and visual artist, who became a highly influential component of the New York City punk rock movement with her 1975 debut album Horses.
Called the "Godmother of Punk", her work was a fusion of rock and poetry. Smith's most widely known song is "Because the Night", which was co-written with Bruce Springsteen and reached number 13 on the Billboard Hot 100 chart in 1978. In 2005, Patti Smith was named a Commander of the Ordre des Arts et des Lettres by the French Minister of Culture, and in 2007, she was inducted into the Rock and Roll Hall of Fame. On November 17, 2010, she won the National Book Award for her memoir Just Kids. She is also a recipient of the 2011 Polar Music Prize.