Sperms are carried in a milky fluid called semen. 'Thick semen' is a term people use to refer to the liquid released after ejaculation (climax) because it contains sperm. Each ejaculation contains around 500 million sperms. In fact most semen, even that released before ejaculation, contains sperm, so do not rely on the withdrawal method and put on a condom as soon as you think you will have sex. If your semen has a thick consistency go to a clinic immediately as it might be an infection.
Attribution: Straight Talk Foundation & Marie Stopes