An anomaly in the process by a a haploid cell is formed from a diploid cells through meiosis. In males, diploid spermatogonia produce two haploid cells (secondary spermatocytes) in meiosis I and four haploid spermatids in meiosis II. In females, primordial germ cells under meiosis II before birth to form primary oocytes. Once puberty cell begins, these cells form secondary oocytes through meiosis II. [from
HPO]