Chromosome analysis of chicken–quail F1 hybrids.
A. Giemsa-stained metaphase spread of a blastodermal cell of the chicken-quail F1 hybrid, consisting of large-sized macrochromosomes and small-sized microchromosomes. B. Hoechst-stained chromosomes of cultured fibroblast cells from embryos of the chicken, chicken–quail hybrid, and quail, which show eight pairs of macrochromosomes and the Z and W sex chromosomes. The sizes of each pair of chromosomes differ between the chicken and quail chromosomes in the hybrid. C. Chromosome painting with macrochromosome-specific DNA probes and hybridization with the W-specific DNA repeat in fibroblast cells of the hybrids. Larger macrochromosomes with stronger hybridization signals are considered to be derived from chicken (GGA, Gallus gallus), and the others from quail (CJA, Coturnix japonica). Scale bars, 10 μm.