<P> Instead of the usual gene repression, some organisms go in for large - scale elimination of heterochromatin, or other kinds of visible adjustment to the karyotype . </P> <Ul> <Li> Chromosome elimination . In some species, as in many sciarid flies, entire chromosomes are eliminated during development . </Li> <Li> Chromatin diminution (founding father: Theodor Boveri). In this process, found in some copepods and roundworms such as Ascaris suum, portions of the chromosomes are cast away in particular cells . This process is a carefully organised genome rearrangement where new telomeres are constructed and certain heterochromatin regions are lost . In A. suum, all the somatic cell precursors undergo chromatin diminution . </Li> <Li> X-inactivation . The inactivation of one X chromosome takes place during the early development of mammals (see Barr body and dosage compensation). In placental mammals, the inactivation is random as between the two Xs; thus the mammalian female is a mosaic in respect of her X chromosomes . In marsupials it is always the paternal X which is inactivated . In human females some 15% of somatic cells escape inactivation, and the number of genes affected on the inactivated X chromosome varies between cells: in fibroblast cells up about 25% of genes on the Barr body escape inactivation . </Li> </Ul> <Li> Chromosome elimination . In some species, as in many sciarid flies, entire chromosomes are eliminated during development . </Li> <Li> Chromatin diminution (founding father: Theodor Boveri). In this process, found in some copepods and roundworms such as Ascaris suum, portions of the chromosomes are cast away in particular cells . This process is a carefully organised genome rearrangement where new telomeres are constructed and certain heterochromatin regions are lost . In A. suum, all the somatic cell precursors undergo chromatin diminution . </Li>

Which type of cell could not be used for karyotyping