Apoptosis in mouse fetal and neonatal oocytes during meiotic prophase oneReport as inadecuate




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BMC Developmental Biology

, 7:87

First Online: 24 July 2007Received: 04 December 2006Accepted: 24 July 2007

Abstract

BackgroundThe 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.

ResultsMicrospreads 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.

ConclusionOur 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.

Electronic supplementary materialThe online version of this article doi:10.1186-1471-213X-7-87 contains supplementary material, which is available to authorized users.

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Author: Fataneh Ghafari - Carlos G Gutierrez - Geraldine M Hartshorne

Source: https://link.springer.com/article/10.1186/1471-213X-7-87







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