Minecraft wiki entry for End_portal, associated text: A Beta 1.9 pre4-style portal as seen in Jeb's live stream. It appears to have slots for eyes of ender.[3]
A fully repaired Beta 1.9 pre3 portal, how it appeared when portals were first released.
An End portal without a silverfish spawner.
An End portal with just a few eyes of ender.
An End portal with all the eyes of ender.
The portal room of a stronghold.
This portal is already activated upon world generation.