Why does x inactivation occurs in female not in male?

Answer 1

Male carry XY genotype whereas female has XX. Two copies of X chromosome means, there is a great chance of potentially toxic double dose of X-linked genes. It is known that 1000s of genes responsible for growth and cell viability are there in X chromosomes.
To avoid the over production of these genes in female (where 2 X chromosomes present), there is a mechanism evolved that transcriptionally control or silence on of these two X chromosome.
http://www.nature.com/scitable/topicpage/x-chromosome-x-inactivation-323

Answer 2

Since there are two X chromosomes in most female animals one of the two becomes an inactive Barry body to facilitate proper cell function. in some animals the inactivation is random in others the X chromosome provided by the male is always inactivated.

Answer 3

Species of animals where the sex chromosomes of females are XX generally produce Barr bodies with only one active X chromosome in each cell. The inactivated X chromosome becomes a Barr body. Male animals with this type of chromosome configuration are either X or XY where the Y chromosome is considerably diminished when compared to the X. X inactivation is random and essentially mimics the functional behavior of the cells of a male animal of the same species making function of somatic cells the same for both sexes. This site has information on this process and can be found by searching for Barr Body.

Answer 4

X inactivation occurs in females to balance the expression of X-linked genes between males and females. Female mammals have two X chromosomes, but only one is needed for normal development and function. X inactivation silences one of the X chromosomes in each cell of a female's body to prevent overexpression of X-linked genes. In males, who have only one X chromosome, X inactivation is not needed.

Answer 5

Because the male already has only one copy of the X chromosome. If females did not have the x inactivation then they would have two copies of the same genes