Commonly, hamsters are thought of as cute, furry, and disposable pets, but the small, rat-like, Chinese hamster serves a totally different function. These rodents are fairly uncommon as pets because they can be difficult to breed. Ironically, the cells of their reproductive organs are what make them so useful to scientists. The Chinese hamster ovary (often abbreviated CHO) tissue is commonly cultured as individual cells in a monolayer and studied worldwide.