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Cytogenetic analysis of pig oocytes matured in vitro

McGaughey, R.W.; Polge, C.

Journal of Experimental Zoology 176(4): 383-395

1971


ISSN/ISBN: 0022-104X
PMID: 5106081
DOI: 10.1002/jez.1401760402
Accession: 014407224

Primary oocytes from the ovaries of prepubertal pigs were removed from small follicles and incubated in a defined culture medium for various periods of time. Evidence was obtained that the oocytes were delayed at diakinesis-metaphase I. When recovered after 42.5-55 hr of culture, 55% of oocytes had reached metaphase II. Of 56 cultured oocytes whose chromosomes were analysed at metaphase I, only one exhibited a chromosomal aberration (19 bivalents + 3 fragments), and one contained 18 bivalents+ 2 monovalents. Of 123 oocytes analysed at anaphase I, telophase I and metaphase II, 27% exhibited chromosomal abnormalities such as heteroploidy, fragments, chromosomal bridges, tripolar spindles and lagging chromosomes. In addition, 31% of 128 oocytes at metaphase II displayed degenerate chromosomes. Of 232 immature oocytes cultured for 42.5-55 hr, only about 20% could be regarded as chromosomally normal, mature secondary oocytes. The delay at diakinesis-metaphase I may be related to a failure of the granulosa cells to supply some substance required by the oocytes.

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