Farelerde Preimplantasyon Döneminde Trofoektoderm ve İç Hücre Kütlesinin Oluşumu

Abstract

Farede fertilizasyon ile başlayan preimplantasyon dönemi sıvı dolu kaviteye sahip blastosistin zona pellusida’dan kurtularak annenin uterus dokusuna implante olması ile son bulur. Erken blastosist, iç hücre kütlesi (ICM) ve trofoektoderm (TE) olarak adlandırılan iki farklı hücre kökeninden meydana gelir. Pluripotent özellik gösteren ICM, farklılaşmamış hücrelerden oluşarak embr yoyu meydana getirir. Trofoblastın progenitörü olan trofoektoderm hücreleri ise ICM’i ve blastosist kavitesini sararak, uterus duvarına implantasyona aracılık eder ve plasentasyona katkıda bulunur. Bu derlemede preimplantasyon döneminde meydana gelen moleküler ve hücresel olaylar açıklanmış, implantasyonun gerçekleşmesi ve gebeliğin sürdürülebilmesi için esansiyel olan, TE, ICM, blastosist kavitesinin oluşumu, bu süreçte anahtar rol oynayan transkripsiyon faktörleri ve hücre polaritesi hakkında bilgi verilmiştir. Bu dönemde yer alan mekanizmaların anlaşılması hem memeli gelişimi hem de klinik açıdan özellikle yapay üreme yöntemlerinin geliştirilmesi bakımından önem taşımaktadır.

Keywords

• Embriyo gelişimi
• preimplantasyon
• TE
• ICM

Formation of Trophectoderm and Inner Cell Mass in Mouse Preimplantation Development

Abstract

Preimplantation development in mouse initiates with fertilization and results in the formation of blastocysts, a fluid filled cavity that is released from zona pellucida and implanted into the mother’s uterine wall. The early blastocysts consists of two distinct cell lineages, called trophectoderm (TE) and inner cell mass (ICM). The pluripotent ICM is an undifferentiated mass of cells that will give rise to the embryo proper. TE is the progenitor of trophoblasts, which surrounds the ICM and blastocyst cavity, mediates blastocyst implantation to the uterine wall, and contributes to placentation. In this review, molecular and cellular events that occur during preimplantation development are described. Additionally, some information was given about formation of TE, ICM, blastocyst cavity and cell polarity and transcription factors playing a key role in this process that are essential for implantation and maintaining the pregnancy. Understanding of such mechanisms is important for mammalian evolution and clinical aspects, particularly for developing the human artificial reproductive technology. 

Keywords

• Embryo development
• preimplantation
• TE
• ICM

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