Board Thread:Questions and Answers/@comment-27127950-20151027213016/@comment-27392440-20160106032911

In the manga they showed grand fisher have his mask broken by force by the arrancar Iceringer long before Aizen got the hogyoku so they show, even before they reveal Aizen I think, that arrancar can easily be made without the hogyoku, they're just strongly implied to be less powerful.