You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is One of the following forms the basis for sex chromatin testing: and explain in detail?
Ans. a, i.e. Barr bodyRef: Gamong 24th/ed, p392-393Barr body forms the basis for sex chromatin testing.Barr BodyWhen two X chromosomes are present in a cell (as in a normal female) one of them becomes inactivated and condensed on the nuclear membrane and is called the 'Barr body'. This process is termed as X chromosome lyonization (inactivation)Presence or absence of Barr bodies helps in ascertaining the sex of an individuals* Absence of Barr body indicates that the patient has only one X chromosome (e.g. Normal male XY or Turner's syndrome (XO)* Nuclei of cells in females (XX) contain a darkly staining Barr body that is not present in the nuclei of cells in males.* Barr bodies are most easily seen in a smear of squamous epithelial cells obtained by scraping the buccal mucosaQ* Barr bodies react differently to histological stains and are best seen as dark staining bodies within the nucleus of non- dividing interphase cells.