Figure 1

Apparatus used to position rats for ultrasound treatment. Parts were cut from Plexiglas unless otherwise noted. A slanted section supported most of the rat's body above the level reached by re-circulating coupling medium. The rat's scrotum was placed within the ultrasound treatment chamber after using a ligature to retain the testes within the scrotum (not shown). The bottom of the treatment chamber was formed of a single layer of latex, which was held in place against a rubber O-ring by an aluminum ring secured by machine screws. This formed a liquid-tight seal, allowing coupling medium to be re-circulated through the treatment chamber and a holding vessel contained within a temperature-regulated water bath (tubing, water bath, plumbing input and output have been omitted for clarity). A ring of ultrasound absorbing material was suspended 1 cm from the bottom of the treatment chamber to aid positioning of the testes and to reduce reflection of ultrasound energy. An ultrasound-transparent, nylon mesh was attached to the bottom of the ring to maintain a minimum distance of 1 cm between the bottom of the ultrasound chamber and the proximal portion of the scrotum.