Oogenesis in humans occurs in ovaries and starts when diploid germ cells
called oogonia grow and mature into primary oocytes enclosed in small follicles.
The primary oocytes start meiosis I, but stop at
prophase I.
Beginning at puberty, periodic hormone secretions induce a few primary oocytes
to complete meiosis I, each producing a non-functional polar body and a haploid
secondary oocyte where most of the cytoplasm from the primary oocyte is concentrated.
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