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The process of spermatogenesis begins with a diploid cell called a spermatogonium, explains SparkNotes. Through a process of chromosomal replication and cell division, spermatogenesis begins when a male starts puberty and creates four haploid sperm cells per meiotic event. A diploid cell contains two copies of each chromosome, while a haploid cell contains one of each, notes Clinton Community College.
Unlike spermatogenesis, which begins during puberty, oogenesis begins before a female mammal is born, explains University of Dayton. Oogenesis begins with a diploid cell called a primary oocyte and, like spermatogenesis, produces four haploid cells, explains SparkNotes. However, only one of those haploid cells goes on to become an ovum cell, while the other three form into polar bodies that die. Once a female begins menstruating, one ovum cell, which first began developing before birth, completes maturation per menstrual cycle.
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