Syringes used to be made of glass, according to my mom, who worked as a lab tech in the 60s. It was a good day when plastic, disposable syringes came into being. Glass syringes had needles that were also reused and had to be sharpened periodically, and everything had to go into the autoclave to be sterilized after every use. Disposable syringes and needles, on the other hand, are guaranteed sterile out of the package. You couldn't always be sure with an autoclave. And needles are no longer re-used, either. My mom said the worst thing was either when a needle had a "burr" on it (because it hurt like the devil) or when a syringe broke. Either event was a serious one.