EN
Differentiation of the suspensor basal cell was studied in Triglochin palustre (2n = 24). The zygote divides into the smaller apical cell and the bigger basal cell, which becomes the basal cell of the suspensor. The nuclear DNA content of the suspensor basal cell attains a high degree of ploidy, up to 256C. Nuclei with the highest ploidy levels of 128C and 256C were observed in mature basal cells (from 50- to 500-celled embryos). As a result of polyploidization the volume of the nucleus increased and changes in the chromatin structure of polyploid nuclei were noted. Endochromocenters at middle ploidy level and bundle-like aggregations of chromatin at the highest ploidy levels were found. Rhythmic enlargement of the DNA content and nuclear volume of the basal cell, as well as the characteristic structure of its chromatin, point to endoreduplication as the mechanism of polyploidization in the suspensor.