What are the homologous and the heterologous portions of the human sex chromosomes?
The Homologous portion is that in which there are genes having alleles in both X and Y sex chromosomes. The homologous portions are located more in the central part of the sex chromosomes, next to the centromere.
The Heterologous portion is that whose genes don't have correspondent alleles in the other sex chromosome and these genes are located more in the peripheral regions of the arms of the Y and X chromosomes.