Related Experiment Video
Updated: Jun 10, 2026
12:11
Analysis of Chromosome Segregation, Histone Acetylation, and Spindle Morphology in Horse Oocytes
Published on: May 11, 2017
The equine oocyte: factors affecting meiotic and developmental competence
1Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843-4466, USA. khinrichs@cvm.tamu.edu
Molecular Reproduction and Development
|July 24, 2010
Summary
Equine oocyte maturation and fertilization present unique challenges. Expanded cumuli oocytes show higher meiotic competence, while delayed recovery improves developmental competence for assisted reproduction in horses.
Area of Science:
- Reproductive Biology
- Animal Science
- Veterinary Medicine
Background:
- Assisted reproduction in horses involves unique oocyte maturation, fertilization, and embryo development processes compared to other species.
- Equine oocyte recovery often requires follicle scraping due to their attachment to the follicle wall.
- Oocyte quality varies based on cumulus morphology and origin (atretic vs. viable follicles).
Purpose of the Study:
- To investigate factors influencing equine oocyte maturation and developmental competence in vitro.
- To compare the meiotic and developmental competence of equine oocytes based on cumulus morphology and recovery conditions.
- To explore effective methods for in vitro fertilization and embryo development in horses.
Main Methods:
- Oocyte recovery via follicle scraping immediately after slaughter or after ovary storage.
- Assessment of meiotic competence (maturation to metaphase II) and developmental competence (blastocyst formation).
- Evaluation of oocytes with expanded cumuli (Ex) versus compact cumuli (Cp) morphology.
- Intracytoplasmic sperm injection (ICSI) for in vitro fertilization and subsequent embryo culture.
Main Results:
- Equine oocytes with expanded cumuli (Ex) exhibit higher meiotic competence than those with compact cumuli (Cp).
- Immediate post-slaughter oocyte recovery yields higher maturation rates than storage, with storage potentially damaging Cp oocyte chromatin.
- Delayed ovary recovery enhances developmental competence, and no difference in blastocyst development exists between Ex and Cp oocytes.
- Intracytoplasmic sperm injection with high glucose medium achieves over 30% blastocyst development.
Conclusions:
- Optimal equine oocyte maturation and development depend on cumulus morphology, recovery timing, and specific in vitro fertilization techniques.
- Understanding these factors is crucial for improving the success rates of assisted reproductive technologies in horses.
- Intracytoplasmic sperm injection offers a viable alternative for equine in vitro fertilization, leading to successful embryo development.
Related Concept Videos
02:07Oogenesis
In human women, oogenesis produces one mature egg cell or ovum for every precursor cell that enters meiosis. This process differs in two unique ways from the equivalent procedure of spermatogenesis in males. First, meiotic divisions during oogenesis are asymmetric, meaning that a large oocyte (containing most of the cytoplasm) and minor polar body are produced as a result of meiosis I, and again following meiosis II. Since only oocytes will go on to form embryos if fertilized, this unequal...
01:22Oogenesis
Oogenesis, the process of developing egg cells (female gametes), occurs within the ovaries and is fundamental to female fertility. This sequence begins during fetal development when diploid oogonia in the developing ovaries undergo mitotic divisions to produce primary oocytes. By birth, these primary oocytes enter prophase I of meiosis but become arrested in this stage, remaining suspended until puberty.
Each primary oocyte is surrounded by a layer of pre-granulosa cells, forming what is known...
Each primary oocyte is surrounded by a layer of pre-granulosa cells, forming what is known...
02:57Meiosis vs. Mitosis
Cell division is necessary for growth and reproduction in organisms. Mitosis aids cell growth and development by dividing somatic cells. In contrast, meiosis causes the division of germ cells and plays an essential role in sexual reproduction. Due to their unique functional requirements, mitosis and meiosis differ from each other in multiple aspects.
Before the start of mitosis and meiosis I, the cell synthesizes DNA, resulting in two homologous copies of each chromosome. DNA synthesis is...
Before the start of mitosis and meiosis I, the cell synthesizes DNA, resulting in two homologous copies of each chromosome. DNA synthesis is...
03:09Meiosis I
Meiosis is the division of a diploid cell into haploid cells forming sperm and eggs in animals through differentiation. Meiosis I is the first stage of meiosis, where the genetic recombination of homologous chromosomes and the reduction of the ploidy level by half occurs.
Prophase I is the most extended and complex step of meiosis I characterized by synapsis, chromosome pairing, and recombination of the homologous chromosomes. This process is facilitated by a proteinaceous structure called the...
Prophase I is the most extended and complex step of meiosis I characterized by synapsis, chromosome pairing, and recombination of the homologous chromosomes. This process is facilitated by a proteinaceous structure called the...
02:02Meiosis II
Meiosis II entails cell division and segregation of the sister chromatids, resulting in the production of four unique haploid gametes. The steps for meiosis II are similar to mitosis, except that meiosis II occurs in haploid cells, whereas mitosis occurs in diploid cells.
The timing and cell division patterns of meiosis differ between males and females. In male meiosis, the centrosomes are part of the formation of the meiotic spindle. However, in oocytes, including that of humans, Drosophila,...
The timing and cell division patterns of meiosis differ between males and females. In male meiosis, the centrosomes are part of the formation of the meiotic spindle. However, in oocytes, including that of humans, Drosophila,...
01:57Meiosis II
Meiosis II is the second and final stage of meiosis. It relies on the haploid cells produced during meiosis I, each of which contain only 23 chromosomes—one from each homologous initial pair. Importantly, each chromosome in these cells is composed of two joined copies, and when these cells enter meiosis II, the goal is to separate such sister chromatids using the same microtubule-based network employed in other division processes. The result of meiosis II is two haploid cells, each containing...