title: DNA replication in the sex chromosomes of the pronghorn and the Rocky Mountain goat.
abstract: The X chromosomes of the male pronghorn (Antilocapra americana) is larger than the "original" type and carries a large segment of late-labelling chromatin. The Y chromosome has a late-labelling segment that appears to duplicate synchronously with that of the X. Both chromosomes have segments that label throughout the period of observation; that the X is about 4.7% of the haploid complement and approaches "original" proportions. The X chromosomes of the Rocky Mountain goat (Oreamnos americanus) appear to be of the "original" type, without marked late-labelling regions, and the Y chromosomes is small. The structure and origin of extra-large sex chromosomes are discussed.
mesh_terms: D000818:Animals; D000866:Antelopes; D001188:Artiodactyla; D004261:DNA Replication; D006041:Goats; D007621:Karyotyping; D008297:Male; D012728:Sex Chromatin; D012730:Sex Chromosomes