(Note graphic descriptions)

BELLEFONTE, Pennsylvania (Reuters) - The defense in the Jerry Sandusky child sex abuse trial wrapped up its case on Wednesday without calling the former Penn State assistant football coach to take the witness stand.

Closing arguments in the closely watched case are expected on Thursday and jury deliberations could begin by the end of the week. Sandusky, 68, is charged with 51 counts of abusing 10 boys over a 15-year period, and faces more than 500 years in prison if convicted on all counts.

The jury is due to be sequestered during its deliberations.

Among its witnesses, the defense called Sandusky' wife of 45 years, Dottie, who testified on Tuesday that she had never seen anything inappropriate in her husband's behavior with children.

On Wednesday, Sandusky's lawyers sought to cast doubt on testimony from an earlier prosecution witness who told jurors he had seen the former coach molesting a boy.

(Editing by Will Dunham)