Hair grows in three stages and catagen is the second phase of this process. It is a transitional phase in which various chemical and structural changes take place. After fall out of hair, the hair follicles remain in a process of to generate a new hair. For bringing or growing a new hair, it needs some preparation to take. You already know that our hair grows and within a few days it starts to regrow. But it is not like after falling out a new hair grows.
Before growing a new hair the hair follicles has to go through some fixed steps. The process involves with decline and degeneration of hair. It is called involution process. This process makes the cells death, which is called apoptosis. At the same time the formation of melanin also is stopped in this stage. In last stage of catagen the dermal papilla starts to rest to hair follicle bulge.
In a study that is recently done shows, if the dermal papilla does not reach o the bulge then at this stage the cycling process does not go on. The follicles also fall out. Some genes responsible for transcription factor which prevents dermal papilla to interact with the stem cell. As a result, people face alopecia permanently.
The catagen stage is responsible for making the old hair shaft drop and prepare the condition for new hair to grow. You may call this stage as “good bye to the old hair” and “welcome to new hair”
Now I will briefly present this complex process in a simple way.
Process of catagen stage
- You hair starts detaching from the roots.
- The hair follicles shrinks from its normal size.
- At the same, time the hair bulb, being pushed to upward anddo not produce any color to the hair shaft.
All most 2%-3% of hair remains in catagen stage. So If you faces some hair fall is not necessarily mean that it is a problem rather it is normal hair growing process.