This type is inactivated and thus does not transcribe. One of the X chromosomes is stainable. An example is sex because it is tightly coiled and therefore will not transcribe. Her other X chromosome does not stain because it is uncoiled, which allows it to transcribe. A normal male does not posess a bar body because he only has one X chromosome.
Some chromatin has portions that begin to transcribe while the rest remains coiled.
These regions are called chromatin puffs. DNA methylation is a type of chemical modification that adds methyl groups to some cytosine bases which prevents transcription in certain genes. DNA methlase is the enzyme which adds this methyl group. The process of crreating more genes of one kind in order to enhance transcription is called Gene Amplification. The duplication of genes results in more DNA per cell instead of only one copy of the gene per cell.