The sex can be identified base on the shape of anal fin, and there are some obvious pearl organs on anal fin of male individuals during reproduction seasons.

可根据臀鳍的形状来鉴别青海湖裸鲤的雌雄，在繁殖期间，雄性个体在臀鳍部位出现明显的珠星。

Results Patient's immunity, age and sex, health habit, hospitalized environment and institution, responsibility of doctor and nurse are the main causes to resulting in patient's anal infection.

结果：病人自身免疫力、年龄与性别、卫生习惯、就医环境及制度、医护人员的责任心等是病人发生肛周感染的主要原因。