Mesoderm lining the coelom forms mesothelium. Separation of Peritoneal and Pleural Cavities: In the adult, peritoneal and pleural cavities are separated by the diaphragm. The diaphragm isformed by a septum transversum, paired pleuroperitoneal folds, and somatic mesoderm.
HIV Myth 2: 'HIV and AIDS Are the Same Thing'. Absolutely not. HIV is the virus that infects a person and attacks the immune system. AIDS is the disease that develops later in people with HIV that remain untreated or don't respond to treatment.
What is AIDS? AIDS is not a virus but a set of symptoms (or syndrome) caused by the HIV virus. A person is said to have AIDS when their immune system is too weak to fight off infection, and they develop certain defining symptoms and illnesses. This is the last stage of HIV, when the infection is very advanced, and if left untreated will lead to death.