oogenesis: begins with ovarian stem cells (oogonia) which are formed into primary oocytes during fetal development, and then are arrested in meiosis until puberty; a surge of luteinizing hormone triggers the resumption of meiosis in a primary oocyte, which transitions to a secondary ooctye; but this cell division does NOT result in 2 identical cells; instead the cytoplasm is divided unequally, and on e daughter cell is much larger than the other; the larger cell eventually will be ovulated, while the smaller cell becomes a polar body and dissintegrates; even though oogenesis produces up to four cells, only one survives; meiosis of a secondary oocyte happens only if a sperm succeeds in penetrating its barriers; then meiosis II resumes, producing one haploid ovum that, at the instant of fertilization becomes the first diploid cell of the new offspring