We are aware that a sperm is the male "gamete" or sex cell.

Each sperm produced by the testis is only a few thousandths of a millimetre in length and must travel through some 30-40 cm (100 000 times its own length) in the male and then in the female reproductive tract before it reaches the Fallopian tubes and can perform the function for which it was intended.

Needless to say, many fewer than 1 in a million ever complete this hazardous journey.

Imagine, only one will make it to fertilize the egg!

Here's a peak of their long journey: