Blastosist gelişimi; hücre soylarının farklanma mekanizmaları

Fertilizasyon sonucu oluşan zigot art arda mitoz bölünmeler geçirir ve ilk 3 mitoz bölünme simetrik olup morfolojik olarak birbirinin aynısı 8 adet blastomer oluşmaktadır. 8 hücreli aşamada embriyoda önemli morfolojik değişiklikler meydana gelir. Bunlar; kompaksiyon, polarizasyon ve asimetrik hücre bölünmesidir. Bu değişikliklerin ardından 8-32 hücreli morula evresinde embriyoda yer alan hücrelerde birincil soy farklanması yani iç hücre kitlesi (ICM) ve dış hücre kitlesi (Trofoektoderm;TE) hücre soyları oluşmaktadır. ICM’den kısa bir süre sonra ikincil soy farklanması denilen epiblast (EPI) ve primitif endoderm (PE) hücre soyları farklanmaktadır. Bu derlemede; preimplantasyon dönemde blastosist gelişim aşamaları sırasıyla ve moleküler yolaklar üzerinden ayrıntılandırılacaktır.

Anahtar Kelimeler:

Blastosist, preimplantasyon, hücre soyları

BLASTOCYST DEVELOPMENT; DIFFERENCE MECHANİSMS OF CELL LAYERS

Zygotes formed after fertilization undergo successive mitotic divisions, the first three mitosis divisions are symmetric and morphologically identical 8 blastomeres are formed. Important morphological changes occur in the embryo in 8-cell stage. These are compaction, polarization, and asymmetric cell division. Following these changes, the primary lineage differentiation in the cells of the embryo in the 8-32 cell morulae, consist of namely inner cell mass (ICM) and outer cell mass (Trofoektoderm; TE). Shortly after the ICM, epiblast (EPI) and primitive endoderm (PE) cell lines differentiate in the process called secondary progeny differentiation. In this review, the stages of blastocyst development in the preimplantation period will be elaborated sequentially and via molecular pathways.

Keywords:

Blastocyst, preimplantation, cell lineage,

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