<Table> <Tr> <Th_colspan="2"> Grey's Anatomy (season 4) </Th> </Tr> <Tr> <Td_colspan="2"> DVD cover art for the fourth season of Grey's Anatomy </Td> </Tr> <Tr> <Th> Starring </Th> <Td> <Ul> <Li> Ellen Pompeo </Li> <Li> Sandra Oh </Li> <Li> Katherine Heigl </Li> <Li> Justin Chambers </Li> <Li> T.R. Knight </Li> <Li> Chandra Wilson </Li> <Li> James Pickens, Jr . </Li> <Li> Sara Ramirez </Li> <Li> Eric Dane </Li> <Li> Chyler Leigh </Li> <Li> Brooke Smith </Li> <Li> Patrick Dempsey </Li> </Ul> </Td> </Tr> <Tr> <Th> Country of origin </Th> <Td> United States </Td> </Tr> <Tr> <Th> No. of episodes </Th> <Td> 17 </Td> </Tr> <Tr> <Th_colspan="2"> Release </Th> </Tr> <Tr> <Th> Original network </Th> <Td> ABC </Td> </Tr> <Tr> <Th> Original release </Th> <Td> September 27, 2007 (2007 - 09 - 27)--May 22, 2008 (2008 - 05 - 22) </Td> </Tr> <Tr> <Th_colspan="2"> Season chronology </Th> </Tr> <Tr> <Td_colspan="2"> ← Previous Season 3 Next → Season 5 </Td> </Tr> <Tr> <Td_colspan="2"> List of Grey's Anatomy episodes </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Grey's Anatomy (season 4) </Th> </Tr>

How many episodes are in season 4 of greys anatomy