The animals used in this laboratory are albino MF1 mice that are at least 4 wk old (30-50 g). Each mouse is stunned by a blow to the head and killed by cervical dislocation. A vertical cut is made through the lower abdominal wall. Removal of the fatty tissue reveals the testes. These can be used to identify the vasa deferentia, each of which is attached to a testis via the epididymis. Gripping the epididymis with forceps, each vas deferens is cut free first from the testis and then from the connective tissue. The vas deferens is then removed from the mouse by cutting through its prostatic end. The isolated vas deferens should now be kept moist in physiological salt solution (solution A). This consists of modified Mg2+-free Krebs solution (118.2 mM NaCl, 4.75 mM KCl, 1.19 mM KH2PO4, 25.0 mM NaHCO3, 11.0 mM glucose, and 2.54 mM CaCl2). Before setting the tissue up in an organ bath, further removal of connective tissue, mesentery, and the epididymis is performed. Thread is attached to both ends of the vas deferens and the tissue mounted in an organ bath. The tissue is attached to a transducer under 0.5g of tension. In the organ bath the tissue is kept in solution A, which is maintained at 33-35°C and continuously bubbled with 95% O2/5% CO2 (see Notes 2 and 3). In this laboratory, 4-mL organ baths are used and vasa deferentia are mounted vertically (Fig. 1).
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