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The X bivalent in fetal bovine oocytes
W Koykul1, M Switonski, P K Basrur
1Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Ontario, Canada.
Hereditas
|January 1, 1997
Summary
Fetal bovine ovaries show X chromosome asynapsis during meiosis, suggesting transcriptional changes may cause these pairing irregularities. This impacts early ovarian differentiation and female fetus development.
Area of Science:
- Reproductive Biology
- Genetics
- Developmental Biology
Background:
- Ovarian differentiation involves complex chromosomal events during meiosis.
- Understanding chromosomal pairing is crucial for reproductive health.
Purpose of the Study:
- To investigate chromosomal pairing irregularities in fetal bovine oocytes.
- To identify the types and incidence of chromosome involvement in these irregularities.
- To explore potential mechanisms behind X chromosome asynapsis.
Main Methods:
- Whole-mount preparations of oocytes from fetal bovine ovaries were analyzed.
- Synaptonemal complexes were examined for pairing irregularities across different developmental stages.
Main Results:
- Chromosomal pairing irregularities, including asynapsis and partial synapsis, were observed in all age groups.
- X chromosomes exhibited a higher frequency of asynapsis and partial synapsis compared to autosomes.
- Autosomal pairing errors were infrequent and stable across studied age groups.
Conclusions:
- X chromosome asynapsis in fetal bovine ovaries occurs more frequently than expected.
- Transcriptional changes of X chromosomes during embryonic and ovarian differentiation may predispose them to structural changes.
- These changes could increase the incidence of sex chromosome asynapsis during early meiosis in female fetuses.