It isn't illegal to chew gum, but it is illegal to bring them into Singapore or sell them except for medical purposes. Since you can't buy gum (selling is illegal) there's no way to chew them so it's almost as good as not being able to chew gum. See this: http://www.customs.gov.sg/leftNa...
Definition: In Vitro. A study done in vitro, in contrast, looks at how a drug or procedure responds in the confines of a test tube or laboratory dish. Clinical trials or medical studies may be performed either in vivo or in vitro.
In vitro fertilization (IVF). IVF, which was first offered in the United States in 1981, is perhaps the most well known method of assisted reproduction. It has resulted in the birth of more than 500,000 children between the years of 1985 and 2006. With IVF, a woman takes fertility drugs to produce more eggs.