The first stage (1~9 years old): before puberty, the breast has not yet developed.

The second stage (10~ 1 1 year): At the early stage of breast development, the breast germ under the nipple began to grow and showed an obvious dome-shaped bulge.

The third stage (12~ 13 years old): the breast becomes round and looks like an adult, but it is still small.

The fourth stage (14~ 15 years old): the breast grows rapidly, and the nipple and areola protrude forward like a ball. If it is still almost the same as when 13 years old, we should find out the reason. As shown in the figure

The fifth stage (16~ 18 years old): normal adult breasts are formed, and the globules of nipple areola are integrated with the round shape of breast.

Specific division

Disc type: the breast is not high, but the bottom is not small, like two thin plates hanging on the chest.

Conical type: the breast bulge is small and the bottom is not big, but the whole breast is hammered and pulled out in a conical shape.

Hemisphere type: The breasts are large and full, just like the two halves of a tennis ball.

Spindle type: the breast bulges very high, but the bottom is not big, which makes the breast protrude forward and slightly droop, like a spindle.

Pendulous type I: the breast is raised but pendulous, and part of the lower side touches the chest.

Pendulous type II: The apex position of the breast is very low, which makes the whole breast hang downward.

The six types of breasts do not change with age, but exist in the population of different ages during the reproductive period. Not only that, everyone's own left and right breasts also have certain differences.