Definition
Sex chromatin, also known as a Barr body, is an inactive X chromosome found in cells of female mammals. It's like a 'dormant' 😴 X chromosome that's been silenced to ensure equal expression of X-linked genes in males and females. Since females have two X chromosomes (XX) and males have one (XY), one X chromosome in females is randomly inactivated during development. This process, called X-inactivation, ensures that females don't produce twice as many X-linked gene products as males. The sex chromatin appears as a darkly stained body in the cell nucleus. Think of it as a visual marker indicating the number of X chromosomes present 🚺.