Most boys begin to slowly expose the glans when they reach puberty, usually fully exposing the coronal sulcus around the age of 14.
After birth, there are adhesions between the inner plate of the foreskin and the coronal sulcus as well as the glans penis.
In general, with age, the adhesion will gradually disappear, at the age of 3 ~ 4 years old, the vast majority of male foreskin and the coronal groove and glans can be separated, some can not be separated automatically, you can try to turn up the foreskin manually separated, generally at the age of 12 years old, with the retraction of the foreskin glans began to be gradually exposed, at the age of 14 years old or so, can be completely exposed to the coronal groove.
However, there are quite a number of boys due to the presence of long foreskin, the glans is always difficult to fully exposed, it is recommended to often upturn and pay attention to clean, if too tight and difficult to upturn or the existence of the foreskin, it is recommended to the hospital as soon as possible to perform circumcision surgery to remove the excessive length of the foreskin.