News | Hebrew University of Jerusalem Team Discovers New Ciliary Structure in Egg Cells, Offering Insight Into Human Infertility
Humans share nearly 70% of their genes with a small tropical fish, the zebrafish. This high degree of similarity, together with transparent embryos and rapid development, has made zebrafish a widely used model organism in biology and medicine.
While observing zebrafish egg cells in real time, a team led by Dr. Yaniv Elkouby at the Hebrew University of Jerusalem (HU) Faculty of Medicine unexpectedly discovered a previously unknown cell structure: a spiral, fiber-like cilium extending from the egg cell into the surrounding cluster of egg cells. The discovery challenges conventional understanding of egg-cell structure and may offer a new direction for studying infertility and miscarriage caused by chromosomal abnormalities in humans.
A Cilium That Moves Chromosomes May Be Crucial to Reproductive Health
Further research showed that the newly discovered cilium is functional. By connecting to the egg cell’s internal “cable system,” it pulls and precisely positions chromosomes during meiosis, helping organize genetic material accurately and systematically as the egg matures.
“This external cilium acts like an anchor, stabilizing the entire chromosome-control mechanism so it can work efficiently and reliably,” Dr. Elkouby explained. This process is critical to healthy egg development and the ability to form a healthy embryo.
The team later found the same structure in zebrafish sperm cells and in mouse egg and sperm cells. This suggests that the cilium may be a widespread, long-overlooked component of germ-cell evolution.
From Fish to Humans: Ciliary Dysfunction May Reveal a New Infertility Mechanism
In human reproduction, errors in chromosome alignment or segregation often cause abnormal embryo development, miscarriage, or infertility. The causes of these errors are not fully understood. This newly identified ciliary structure, closely involved in chromosome organization, may be a missing part of the explanation.
Some rare genetic disorders known as ciliopathies are already known to cause reduced fertility and serious developmental disorders in infants and children. These problems have generally been attributed to other known types of cilia. The discovery of this new cilium offers another possible explanation.
As Dr. Elkouby noted, “Identifying these mechanisms brings us one step closer to finding solutions.”
Advanced Cell and Imaging Research
To observe the cilium’s dynamic function, the team developed and used advanced methods including high-resolution live microscopy, three-dimensional imaging, ovarian tissue culture, laser ablation and manipulation, and multiple genetic mutation analyses. Together, these techniques provided the first clear view of the structure and its function.
The study was co-led by Dr. Elkouby’s doctoral students Avishag Mytlis and Vineet Kumar, with international collaboration from Dr. Sudipto Roy’s laboratory at the Institute of Molecular and Cell Biology (Proteos) in Singapore and Dr. Ruxandra Bachmann-Gagescu’s laboratory at the University of Zurich.
The findings were published in Science in a paper titled “Biomechanical control of meiotic chromosomal bouquet and germ cell morphogenesis by the zygotene cilium.”
News | Hebrew University of Jerusalem Team Discovers New Ciliary Structure in Egg Cells, Offering Insight Into Human Infertility
News | Hebrew University of Jerusalem Team Discovers New Ciliary Structure in Egg Cells, Offering Insight Into Human Infertility
Humans share nearly 70% of their genes with a small tropical fish, the zebrafish. This high degree of similarity, together with transparent embryos and rapid development, has made zebrafish a widely used model organism in biology and medicine.
While observing zebrafish egg cells in real time, a team led by Dr. Yaniv Elkouby at the Hebrew University of Jerusalem (HU) Faculty of Medicine unexpectedly discovered a previously unknown cell structure: a spiral, fiber-like cilium extending from the egg cell into the surrounding cluster of egg cells. The discovery challenges conventional understanding of egg-cell structure and may offer a new direction for studying infertility and miscarriage caused by chromosomal abnormalities in humans.
A Cilium That Moves Chromosomes May Be Crucial to Reproductive Health
Further research showed that the newly discovered cilium is functional. By connecting to the egg cell’s internal “cable system,” it pulls and precisely positions chromosomes during meiosis, helping organize genetic material accurately and systematically as the egg matures.
“This external cilium acts like an anchor, stabilizing the entire chromosome-control mechanism so it can work efficiently and reliably,” Dr. Elkouby explained. This process is critical to healthy egg development and the ability to form a healthy embryo.
The team later found the same structure in zebrafish sperm cells and in mouse egg and sperm cells. This suggests that the cilium may be a widespread, long-overlooked component of germ-cell evolution.
From Fish to Humans: Ciliary Dysfunction May Reveal a New Infertility Mechanism
In human reproduction, errors in chromosome alignment or segregation often cause abnormal embryo development, miscarriage, or infertility. The causes of these errors are not fully understood. This newly identified ciliary structure, closely involved in chromosome organization, may be a missing part of the explanation.
Some rare genetic disorders known as ciliopathies are already known to cause reduced fertility and serious developmental disorders in infants and children. These problems have generally been attributed to other known types of cilia. The discovery of this new cilium offers another possible explanation.
As Dr. Elkouby noted, “Identifying these mechanisms brings us one step closer to finding solutions.”
Advanced Cell and Imaging Research
To observe the cilium’s dynamic function, the team developed and used advanced methods including high-resolution live microscopy, three-dimensional imaging, ovarian tissue culture, laser ablation and manipulation, and multiple genetic mutation analyses. Together, these techniques provided the first clear view of the structure and its function.
The study was co-led by Dr. Elkouby’s doctoral students Avishag Mytlis and Vineet Kumar, with international collaboration from Dr. Sudipto Roy’s laboratory at the Institute of Molecular and Cell Biology (Proteos) in Singapore and Dr. Ruxandra Bachmann-Gagescu’s laboratory at the University of Zurich.
The findings were published in Science in a paper titled “Biomechanical control of meiotic chromosomal bouquet and germ cell morphogenesis by the zygotene cilium.”
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