Sperms are formed in testis which are present in a sac like structure hanging below penis. The sac is called scrotum . It is covered by a soft skin and a muscle called Detrusor .

This is the only human organ needing less than normal body temperature of 37 degree Celsius for its optimal functioning. This temperature is maintained very well by detrusor muscle . In winter, it remains contracted to preserve heat and in summer , it relaxes a bit to lose heat so that the needed temperature of 35.5 degrees Celsius is maintained . In extreme winter or in extreme heat, formation and activity of sperms may be affected . 

There are two testis ; one on each side forming a inverse hockey shaped structure called epididymis. This ultimately opens in to a tube called vas deference which carry the mature sperms to mix with seminal fluid from seminal vesicles and prostate . Sperms mixed with Seminal fluid forms Semen which is expelled out during sexual intercourse . The average quantity of semen in a normal human being is 2-5 ml .

After the semen is deposited in vagina, there is liquefaction so that sperms can swim to the mouth of the womb of woman. The pathway in penis is made favourable by secretion from para urethral and Cowper glands . The alkaline environment is a must for the survival of delicate sperms. 

Many believe that the clear and watery secretion from these glands is abnormal while a lot of others mistake it to be Semen . People get so much occupied that they develop weakness, tiredness, giddiness due to anxiety. It is called Dhat Syndrome