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Updated: Aug 16, 2026
12:11
Analysis of Chromosome Segregation, Histone Acetylation, and Spindle Morphology in Horse Oocytes
Published on: May 11, 2017
Oocyte morphology in dominant and subordinate follicles
1Department of Anatomy and Physiology, Royal Veterinary and Agricultural University, Frederiksberg, Denmark.
Molecular Reproduction and Development
|March 1, 1994
Summary
Oocyte maturation in cattle involves structural changes in dominant follicles, preparing them for ovulation. Subordinate oocytes show degeneration, highlighting the importance of follicular dominance for reproductive success.
Area of Science:
- Reproductive Biology
- Veterinary Science
- Cell Biology
Background:
- Follicular dominance is crucial for selecting a single ovulatory follicle.
- Oocyte quality is influenced by the follicular environment and hormonal milieu.
- Understanding oocyte structural dynamics is key to improving fertility.
Purpose of the Study:
- To investigate the structural changes in oocytes from dominant and subordinate follicles in cattle.
- To correlate these structural changes with follicular fluid hormone concentrations (estradiol-17 beta and progesterone).
- To determine the morphological prerequisites for oocyte maturation and competence.
Main Methods:
- Oocyte aspiration from dominant and subordinate follicles in heifers and cows.
- Transmission electron microscopy for ultrastructural analysis of oocytes.
- Follicular fluid analysis for estradiol-17 beta (E2) and progesterone (P4) concentrations.
Main Results:
- Dominant oocytes exhibited increased lipid droplets and decreased Golgi complex size, with changes in nuclear envelope and microvilli stacks.
- Pre-ovulatory LH surge induction led to reduced oocyte-cumulus contact and nuclear alterations in dominant oocytes.
- Subordinate oocytes showed degenerative features, with follicular fluid dominated by progesterone (P4).
Conclusions:
- Morphological changes in dominant oocytes before the LH surge are essential for maturation competence.
- Subordinate oocytes undergo degeneration, indicating selection mechanisms within follicular waves.
- Hormonal milieu (E2:P4 ratio) within follicles influences oocyte quality and fate.
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