In its latest move to broaden its iPod and iTunes franchises, Apple Computer Inc. has introduced "iTunes U," a nationwide expansion of a service that makes course lectures and other educational materials accessible via Apple's iTunes software.

The company behind the iPod portable players, the iTunes online music store and Macintosh computers had been working with six universities on the pilot project for more than a year and expanded the educational program this week, inviting other universities to sign up.

Internet access to college lectures is nothing new, but listening to them on portable gadgets is a more recent phenomenon of the digital age, spurred in part by the popularity of podcasts, or downloadable audio files.

The University of Missouri offered podcasts of lectures through its school network before it signed up with Apple last summer as a pilot school. But "iTunes U" offered a software and service package for free, said Keith Politte, the development officer at the university's School of Journalism.

The market dominance of Apple's iTunes Music Store and iPods, which helped spawn the podcast movement, also was key.

"Our students are digital natives. We seek to meet our students where they are, and iTunes is the interface that most of our students are already familiar with," Politte said.

Apple's service offers universities a customized version of the iTunes software, allowing schools to post podcasts, audio books or video content on their iTunes-affiliated Web sites.

The iTunes-based material will be accessible on Windows-based or Macintosh computers and transferable to portable devices, including Apple's iPods.

The service lets institutions decide if they want to limit access to certain groups or open the material to the public.

For instance, Stanford University, which joined the pilot program last fall, gives the public free access not only to some lectures but also audio broadcasts of sporting events through its iTunes-affiliated site.

Schools and universities have historically been major contributors to Apple's computer sales. With iTunes U, Apple "is leveraging the ubiquity that we've established on campuses with iPods and iTunes," said Chris Bell, Apple's director of product marketing for iTunes.