However, in 2011, fertility specialists at Hull and Princeton published an important research paper. They tested 27 men and found that 37% of men had active sperm before ejaculation. The rest is not. Obviously, some men have a chance to become pregnant for the first time. Cartilage is a firm but pliable connective tissue in the joint. It protects and exerts pressure on the joints by absorbing the pressure and vibration generated during the movement. This reduction in the normal amount of cartilage tissue can cause some forms of arthritis. What was then defined as the penetration of the penis to the vagina has now had varieties like oral and anal sex. Some arthritis, such as rheumatoid arthritis and lupus, affects multiple organs and causes a wide range of symptoms.