PSY 302 Chapter Notes - Chapter 2: Inner Cell Mass, Prenatal Development, Twin
6 Feb 2017
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Preformationism: thought tiny being was in head of sperm cell and enlarged once it entered the egg. Did not agree with preformation due to epigenesis (emerging of structures/functions as development proceeds) he examined eggs development into chicks. Involves union of gametes (reproductive cell sperm and egg) Each contains half the genetic info from each cell 23 chromosomes (through process of meiosis) Women produce eggs during prenatal period, men constantly produce sperm. Egg is largest body cell seen with naked eye, sperm among smallest. Begins with egg leaving ovary and entering fallopian tube. Travels through tube to uterus release a chemical that attracts sperm towards it. Intercourse must occur around time of egg release to ensure union of gametes. About 500 million sperm cells released with each ejaculation. Sperm travels about 6 hours, 6-7 in from vagina to fallopian tube only about 200/500 million make it to the egg.
