iTunes 10.5.3 version contain the following new features and changes:
What’s new in iTunes 10.5.3
iTunes 10.5.3 allows you to sync interactive iBooks textbooks to your iPad. These multi-touch textbooks are available for purchase from the iTunes Store on your Mac or from the iBookstore included with iBooks 2 on your iPad.
iBooks textbooks are created with “iBooks Author” — now available as a free download on the Mac App Store.
Download iTunes 10.5.3:
iTunes 10.5.3 can be downloaded either by using the built-in software updater or by downloading and installing the standalone executable file from Apple’s website.