A SIMPLE METHOD OF HYPOPHYSECTOMY IN RATS

Abstract

The anesthetized rat is placed on its abdomen on a holding apparatus or in the left hand of the operator. A lumbar puncture needle is held in the right hand and carefully inserted into the external auditory canal. After perforating the tympanic membrane the needle is slid along the upper wall of the tympanum until its tip is fixed to a small channel of the inside wall of the tympanum. A slight push is given to the needle and the thin bone wall of the tympanum is broken through; the oblique face of the tip of the needle is then located above the pituitary body. The pituitary is then removed with a 5 ml syringe. The needle should be removed from the auditory canal amost simultaneously with the suction movement. It is remarkable that in young rats weighing from 50 to 60 g the direct distance between the pituitary body and the opening of the auditory canal is 13 mm and is perpendicular to the midline of the body. As rats grow larger, the pituitary body assumes a location slightly more rostral in respect to the opening of the auditory canals. If the operator becomes skilled in this procedure, hypophysectomy can be carried out within five minutes.