SAN FRANCISCO -- An anti-doping expert Thursday told the jury in Barry Bonds' perjury trial that use of steroids and human growth hormone can lead to enlarged or shrinking body parts.

The statements were by Larry Bowers, senior managing director of the U.S. Anti-Doping Agency. On Wednesday, Steve Hoskins, a childhood friend and former business partner of Bonds, testified the size of the career home run leader's hands and feet grew before he retired from baseball in 2007.

Defense attorney Allen Ruby claimed there are no studies proving HGH affects body parts and that all evidence is anecdotal. "Is it your opinion that if someone takes human growth hormone, then their head will get big?'' Ruby asked Bowers.

Ruby also cross-examined Hoskins, claiming the man who once managed Bonds' memorabilia business is trying to get even with him after being fired because Bonds found out he was stealing from the business.

Bonds is accused of lying in December 2003 to a federal grand jury investigating the Bay Area Laboratory Co-Operative, which developed performance-enhancing drugs for Bonds, former Yankee Jason Giambi, track star Marion Jones and others.

Bowers' statements were part of the prosecution's case to prove a scientific foundation for the expected testimony from Bonds' former girlfriend Kimberley Bell.

"If you take anabolic steroids,'' Bowers said, "it has been well documented that you can have testicular atrophy.''

Prosecutors have said Bell saw Bonds' body exhibiting acne, hair loss and testicular shrinkage.

The trial is recessed until Monday, when Bell might appear.

Notes & quotes: Mark Geragos, attorney for Greg Anderson, Bonds' onetime trainer, filed a one-page request with U.S. District Judge Susan Illston asking for an evidentiary hearing to contest the order putting Anderson behind bars. Anderson refused to testify Tuesday and for a third time was jailed on contempt . . . An attorney for Roger Clemens was in the courtroom taking notes, presumably preparing for Clemens' perjury trial, scheduled in Washington this summer.

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