Anatomy of the menisci can be seen forming in a baby which is inside the mother around the 10th week of fetal development. The menisci holds a lot of cells and is a channel for blood. During the development of the menisci there is a decrease of cells but an increase of insluble fibrous protien in the menisci. The blood vessals also retreat to the outer boundary of the knee. This occurs before birth and a little after birth. This happens because of joint motion and the weight it bears. These changes mostly happen and are the most important between the ages of 1 and 3 which are still postnatal. Menisci grow in a ratio to the tibial plateau. The meniscus is composed of 75% water approximately. It's also made of collagen fibers (which is insoluble fibrous protien), noncollagenous protiens, hexosamines (which are unprotective in some metabolic deseases), and fibrochondrocytes. The radial fibers provide rigidity while other fibers resist tension.