How Does the Nail Plate Grow?

As keratin cells are pushed from the matrix they begin to change. They slowly lose their plump, round shape, as shown in Figure 2.2. When they flatten, most of the whitish material inside the cell is lost. They become thin, flat, transparent nail cells. If you recall, the distal part of the matrix is just below the lunula. Most of the lunula area cells haven’t completely flattened or lost their inner material. This explains why the lunula is whitish and cloudy. When the cells flatten, they also become more compact. Older cells pack together more tightly making the nail plate harder or more dense, so near the eponychium (proximal nail plate), the plate is softer. The free edge contains the oldest, flattest, and hardest cells.

It is very important to treat the area near the cuticle with care. It is thinner and softer than the rest of the plate. Also, the matrix is directly below this region. Remember, the eponychium tissue is a barrier against bacteria and other microscopic invaders. It must not be broken or harmed. Always use caution with any procedure involving this area of the nail unit. Damage here can permanently injure the nail unit.

For many years, it was believed that at least part of the nail plate grew up from the nail bed. Every cell in the nail plate comes from the matrix. The only exception is the thin layer of epidermis that adheres to the bottom of the plate. This tissue becomes the solehorn found under the free edge of the plate.