Y-CHROMOSOME AND HETEROCHROMATIN IN RUMEX ACETOSA

抄録

A cytological study was made mainly on the Y-chromosomes in connection with chromocenters in Rumex acetosa L. At mid-prophase in somatic cells, the Y₁-chromosome was found to consist of two different segments besides the centromere: one is derived from the chromocenter, another is euchromatic, but different in condensation from the euchromatic part of the X-chromosome and also of the autosomes. The Y₂ has sometimes a dim or hyaline small segment at the distal end of the long arm besides those two segments as found in the Y₁. Furthermore, at mid-prophase the Y-chromosomes are, on the whole, more darkly stained than any other chromosome. Then, the Y's can be said to be entirely heteropycnotic at this stage, in spite of showing a partial heteropycnosis at early prophase and interphase where the distal part of the short arm revealed itself as a chromocenter.