In vivo means in life, so something would be the whole, living organism that the scientist is using as a scientific subject. It is best for "observing the overall effects of an experiment on a living subject."
In vitro means in the glass, so it means the experiment is carried out outside of the organism, usually in a test tube or petri dish. The advantage is that the experiment can be more precisely controlled; the disadvantage is that it "may lead to results that do not correspond to the situation that arises in a living organism."
I rarely hear "ex vivo"; the definition is that it "refers to experimentation or measurements done in or on living tissue in an artificial environment outside the organism with the minimum alteration of the natural conditions."
In vitro means in the glass, so it means the experiment is carried out outside of the organism, usually in a test tube or petri dish. The advantage is that the experiment can be more precisely controlled; the disadvantage is that it "may lead to results that do not correspond to the situation that arises in a living organism."
I rarely hear "ex vivo"; the definition is that it "refers to experimentation or measurements done in or on living tissue in an artificial environment outside the organism with the minimum alteration of the natural conditions."
Source(s):
http://en.wikipedia.org/wiki/In_vivo
http://en.wikipedia.org/wiki/In_vitro
http://en.wikipedia.org/wiki/Ex_vivo
http://en.wikipedia.org/wiki/In_vitro
http://en.wikipedia.org/wiki/Ex_vivo
in vitro主要泛指体外实验，不涉及体内实验内容； 而比较in vivo和ex vivo，两个词的运用比较主要在基因治疗方面，转入目的基因方法。in vivo指活体直接转移，将带有遗传物质的病毒、脂质体或裸露DNA直接注射到实验动物或人体内；ex vivo指在体转移，将实验对象的细胞取出，体外培养并导入重组基因，而后将这些经遗传修饰的细胞重新输回实验动物体内。
ex vivo：活体外 in vivo：活体内实验 in vitro：试管等内的体外实验