Apoptosis in mouse fetal and neonatal oocytes during meiotic prophase one

Background The vast majority of oocytes formed in the fetal ovary do not survive beyond birth. Possible reasons for their loss include the elimination of non-viable genetic constitutions arising through meiosis, however, the precise relationship between meiotic stages and prenatal apoptosis of oocytes remains elusive. We studied oocytes in mouse fetal and neonatal ovaries, 14.5–21 days post coitum, to examine the relationship between oocyte development and programmed cell death during meiotic prophase I. Results Microspreads of fetal and neonatal ovarian cells underwent immunocytochemistry for meiosis- and apoptosis-related markers. COR-1 (meiosis-specific) highlighted axial elements of the synaptonemal complex and allowed definitive identification of the stages of meiotic prophase I. Labelling for cleaved poly-(ADP-ribose) polymerase (PARP-1), an inactivated DNA repair protein, indicated apoptosis. The same oocytes were then labelled for DNA double strand breaks (DSBs) using TUNEL. 1960 oocytes produced analysable results. . Oocytes at all stages of meiotic prophase I stained for cleaved PARP-1 and/or TUNEL, or neither. Oocytes with fragmented (19.8%) or compressed (21.2%) axial elements showed slight but significant differences in staining for cleaved PARP-1 and TUNEL to those with intact elements. However, fragmentation of axial elements alone was not a good indicator of cell demise. Cleaved PARP-1 and TUNEL staining were not necessarily coincident, showing that TUNEL is not a reliable marker of apoptosis in oocytes. Conclusions Our data indicate that apoptosis can occur throughout meiotic prophase I in mouse fetal and early postnatal oocytes, with greatest incidence at the diplotene stage. Careful selection of appropriate markers for oocyte apoptosis is essential

Oocyte progression and death during first meiotic prophase

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Apoptosis in mouse fetal and neonatal oocytes during meiotic prophase one-1

<p><b>Copyright information:</b></p><p>Taken from "Apoptosis in mouse fetal and neonatal oocytes during meiotic prophase one"</p><p>http://www.biomedcentral.com/1471-213X/7/87</p><p>BMC Developmental Biology 2007;7():87-87.</p><p>Published online 24 Jul 2007</p><p>PMCID:PMC1965470.</p><p></p>ves of pachytene on 17 and 20 dpc. Note also the persistence of some pre-diplotene stages of oocytes until day 21, two days after birth

Apoptosis in mouse fetal and neonatal oocytes during meiotic prophase one-0

<p><b>Copyright information:</b></p><p>Taken from "Apoptosis in mouse fetal and neonatal oocytes during meiotic prophase one"</p><p>http://www.biomedcentral.com/1471-213X/7/87</p><p>BMC Developmental Biology 2007;7():87-87.</p><p>Published online 24 Jul 2007</p><p>PMCID:PMC1965470.</p><p></p>c prophase I

Apoptosis in mouse fetal and neonatal oocytes during meiotic prophase one-2

<p><b>Copyright information:</b></p><p>Taken from "Apoptosis in mouse fetal and neonatal oocytes during meiotic prophase one"</p><p>http://www.biomedcentral.com/1471-213X/7/87</p><p>BMC Developmental Biology 2007;7():87-87.</p><p>Published online 24 Jul 2007</p><p>PMCID:PMC1965470.</p><p></p>ling using the TUNEL metho

Apoptosis in mouse fetal and neonatal oocytes during meiotic prophase one-4

<p><b>Copyright information:</b></p><p>Taken from "Apoptosis in mouse fetal and neonatal oocytes during meiotic prophase one"</p><p>http://www.biomedcentral.com/1471-213X/7/87</p><p>BMC Developmental Biology 2007;7():87-87.</p><p>Published online 24 Jul 2007</p><p>PMCID:PMC1965470.</p><p></p>c prophase I