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Oocyte competence develops: nuclear maturation synchronously with cytoplasm maturation

Published online by Cambridge University Press:  18 November 2024

Hossein Torkashvand Open the ORCID record for Hossein Torkashvand [Opens in a new window] ,
Ronak Shabani ,
Tayebe Artimani ,
Iraj Amiri ,
Shamim Pilehvari ,
Leila Torkashvand ,
Rana Mehdizadeh  and
Mehdi Mehdizadeh Open the ORCID record for Mehdi Mehdizadeh [Opens in a new window]
Hossein Torkashvand
Affiliation:
Department of Anatomical Science, School of Medicine, Iran University of Medical Sciences, Tehran, Iran Fertility and Infertility Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
Ronak Shabani
Affiliation:
Reproductive Sciences and Technology Research Center, Department of Anatomy, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
Tayebe Artimani
Affiliation:
Fertility and Infertility Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
Iraj Amiri
Affiliation:
Fertility and Infertility Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
Shamim Pilehvari
Affiliation:
Fertility and Infertility Research Center, Hamadan University of Medical Sciences, Hamadan, Iran Clinical Research Development Unit of Fatemieh Hospital, Department of Gynecology, Medicine School, Hamadan University of Medical Sciences, Hamadan, Iran
Leila Torkashvand
Affiliation:
Fertility and Infertility Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
Rana Mehdizadeh
Affiliation:
School of Dentistry, Central Tehran Branch, Islamic Azad University, Tehran, Iran
Mehdi Mehdizadeh*
Affiliation:
Reproductive Sciences and Technology Research Center, Department of Anatomy, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
*
Corresponding author: Mehdi Mehdizadeh; Email: mehdizadeh.m@iums.ac.ir
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Summary

Human oocyte maturation is a lengthy process that takes place over the course of which oocytes gain the inherent ability to support the next developmental stages in a progressive manner. This process includes intricate and distinct events related to nuclear and cytoplasmic maturation. Nuclear maturation includes mostly chromosome segregation, whereas rearrangement of organelles, storage of mRNAs and transcription factors occur during cytoplasmic maturation.

Human oocyte maturation, both in vivo and in vitro, occurs through a process that is not yet fully understood. However, it is believed that the second messenger, cyclic adenosine monophosphate (cAMP), plays a pivotal role in the upkeep of the meiotic blocking of the human oocyte. Relatively high levels of cAMP in the human oocyte are required to maintain meiosis blocked, whereas lower levels of cAMP in the oocyte enable meiosis to resume. Oocyte cAMP concentration is controlled by a balance between adenylate cyclase and phosphodiesterases, the enzymes responsible for cAMP generation and breakdown.

In addition to nuclear maturation, the female gamete requires a number of complicated structural and biochemical modifications in the cytoplasmic compartment to be able to fertilize normally. According to ultrastructural studies, during the transition from the germinal vesicle stage to metaphase II (MII), several organelles reorganize their positions. The cytoskeletal microfilaments and microtubules found in the cytoplasm facilitate these movements and regulate chromosomal segregation.

The aim of this review is to focus on the nuclear and cytoplasmic maturation by investigating the changes that take place in the process of oocytes being competent for development.

Keywords

cytoplasmic maturationdevelopmentmeiosisnuclear maturationoocytes

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Type
Review Article
Information
Zygote , Volume 32 , Issue 6 , December 2024 , pp. 421 - 428
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© The Author(s), 2024. Published by Cambridge University Press

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