[Organization of centromere regions of chromosomes in the lampbrush phase].

ABSTRACT

Centromeres have a pivotal role in the complex of structural elements that are required for precise segregation of eukaryotic chromosomes during two types of cellular divisions--mitosis and meiosis. Data of ultrastructural and cytomolecular analysis indicate significant changes in molecular composition and functional morphology of centromeres during preparation for the first meiotic division. The review is devoted to modern concepts of morpho-functional organization of chromosomal centromere regions in growing oocytes in birds and amphibians. Structure, molecular composition as well as domain organization of centromeres in the lampbrush phase are characterized; data of cytogenetic analysis are presented. Special attention is given to the significance and regulation of satellite DNA transcription in the nuclei of developing oocytes. Possible functions of centromere "protein bodies" formed at the primary constriction of meiotic bivalents are discussed.