In Parascaris the mitotic chromosomes of gonial germline cells are holocentric and possess a continuous kinetochore along their entire length. By contrast, in meiotic cells, the centromeric activity is restricted to the heterochromatic tips where direct insertion of spindle microtubules into chromatin without any kinetochore plate is seen. In the presomatic cells of early embryos, which undergo...

by Nagorsen et al. (1995), who found that the proposed Paleobiologists generally agree that within the past 10,000 yr relation appears to hold in that region. North American black bears (Ursus americanus) have decreased Along the same lines, Graham (1991, p. 237), reporting in body and tooth size. Some researchers infer that diminution work on late Quaternary black bears in the mid-continent, w...

The previously published data are examined on the base of the hypothesis about existence of differential polyteny of chromosomes and excess chromatin diminution during the first stages of embryogenesis. It has been concluded that available data provide the genetic proof that chromatin diminution is one of the mechanisms underlying the origin of polymorphism in sugar beet agamospermous progenies...