[The first and second polar bodies in mouse oogenesis].

Using light and electron microscopy, we studied several characteristics of the interphase nuclei and mitotic chromosomes in embryonic cells Cyclops kolensis (Lill) before and after chromatin diminution. We detected the reduction of one of the two nucleoli in somatic cells resulting from chromatin diminution. However, the ratio of the total diameter of the nucleoli to the diameter of the nucleus or to the diameter of the cell remains unchanged. Granules of the chromatin to be eliminated become visible in somatic cells of the C. kolensis embryos at the interphase of the fourth cleavage division. The structure of interphase nuclei and mitotic chromosomes of somatic cells of C. kolensis embryos is different before and after chromatin diminution. Possible mechanisms underlying these differences are discussed.