A final period of extension was carried out for 9 min and final holding at 4 . the pcr products were resolved after electrophoresis in 2 % agarose gel with ethidium bromide . the pcr products were visualized while the gel was exposed to ultraviolet light 扩增产物在2琼脂糖凝胶上电泳，用pcrmarker作分子量标准，紫外灯下观察，最适pcr反应条件为扩增出最强的sry产物带而无非特异性扩增带出现时的反应条件。
