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Thanks to the study of zebrafish, researchers have identified a mechanism that explains fertility problems in humans

 University researchers have identified a new type of organelle that has not been discovered in gametes before. According to them, failure of its function causes infertility because it is responsible for the organization of the chromosomes in the gametes: "The discovery advances us towards finding medical solutions"

Zebra fish. Image:
Zebra fish. Image:

For years, medicine has been searching in the living world for human-like models in order to reveal the secrets of the human body and help cure diseases. In addition to a long list of similarities, some of you may be surprised to learn that we share about 70% of our genes with the zebrafish - a fact that makes it an ideal animal model for studying human diseases and biological processes. A new study, which relied on the development of egg cells in zebrafish, revealed one of the mechanisms that defects in it lead to fertility problems in humans as well. The study was conducted in the laboratory of Dr. Yaniv Alkoubi from the Faculty of Medicine at the Hebrew University and was recently published in the prestigious journal Science.

Ovaries of zebrafish: the stages of early gamete development are similar to humans

Together with The doctoral students Avishag Maitlis and Vinit Komar, Dr. Elkoubi studied zebrafish ovaries, in which the stages of early gamete development are very similar to those in humans. In one of the experiments, the team of researchers identified an organ in the form of a split fiber, which had not been discovered for more than a hundred years of research in the field. The fiber is observed coming out of the cell, stretching out and twisting between the eggs in the cluster where they develop. "This organelle is formed in the egg in its early stages of development and is called 'cilium' (plural cilia), or eyelash in Hebrew. We found that the cilium is critical to the process of division of the nucleus in the gametes and actually controls the mechanics of the chromosomes, which is necessary for the creation of gametes and fertility." Dr. Alkobi explains. Later, the researchers identified the same organelle in the sperm cells of zebrafish, and even in the eggs and sperm of mice. Through the use of microscopy, innovative visualizations and genetic analyses, the researchers were able to identify and map the roles of cilia in oocytes in zebrafish ovaries.

The function of the cilium is considered particularly critical and defects in it are very common and lead to fertility problems in humans, but until now the mechanism leading to them was unknown. Dr. Alkobi shares that "Failure to organize the chromosomes within the human egg and sperm cells is the common cause of miscarriages and infertility, but the mechanisms of the failure are not clear. In fact, the discovery of the new type of cilia which plays an essential role in chromosomal organization opens completely new research directions and can provide insights that will advance us towards finding medical solutions."

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