The operating board shown in the Plate was developed to facilitate parapharyngeal hypophysectomy in the mouse. It is essential for this operation to rigidly secure the animal, and to gently retract the trachea, muscles and blood vessels in the neck region. Moreover, as deeper tissues are dissected, the tension of the retractors holding the superficial layers must be constantly adjusted to 'take up the slack' and more clearly expose the base of the cranium. Retractors attached to rubber-bands, chain or string held in cleats at the side of the operating boards commonly in use, proved to be much inferior to those described here.
The operating board consists of a plastic-covered wood and metal base and small powerful pot magnets ('Eclipse'), some of which hold the animal in the operating position, whilst others anchor the incision retractors. The board is robust, easy