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.
Using a process called in vitro activation (IVA), the scientists take an ovary, or piece of ovarian tissue, and treat it outside the body with proteins and other factors that normally prompt immature follicles to mature into eggs. The recharged tissue is then reimplanted into the womenâs ovaries. Among the 27 women who volunteered in the small study, five were able to produce viable eggs, one is pregnant, and another gave birth to a healthy baby.