Osteosarcoma is the most common primary malignant bone cancer. It most commonly affects younger males between 10 and 25 years old, but can less commonly affect older adults. It often occurs in the long bones of the arms and legs at areas of rapid growth around the knees and shoulders of children. This type of cancer is often very aggressive with risk of spread to the lungs. The five-year survival rate is about 65%. It starts in immature bone cells that normally form new bone tissue.

Masturbation is a process where a person derives sexual pleasure by manually stroking his genitals by his hands. It is usually performed by singletons but those in a relationship may also perform it to get an orgasm. It is a normal activity that has no harmful physical or emotional effects. On the contrary, it can be beneficial in some ways. Excessive masturbation can have some harmful effects, which are discussed here.

Morphology refers to the shape and structure of the sperm. A normal-looking sperm has an oval head and a tail seven to 15 times longer than the head. On a semen analysis, in which we look at sperm under the microscope, we can identify defective sperm by their large heads or strange tails -- kinked, doubled, or coiled.

People who gain belly fat are at greater risk of serious health problems than are people who accumulate fat in other areas and men are more likely than women to gain weight around the waist. The genes can affect the chances of being overweight or obese, as well as where you carry extra fat on your body. For most men, however, the problem likely has more to do with lifestyle than inherited traits.

Bent penis is abnormal bending or curvature of the penis. Peyronie's disease is a severe curvature of the erect penis. Many men have a slight curve of the penis. As long as there is no pain or problem with sexual performance, men with a slightly curved penis should not be concerned and do not need to see a doctor.