Hair follicle miniaturisation that precedes long before its death
During hair thinning or balding process which could happen due to a variety of reasons – terminal hair progresses back into vellus hair during hair follicle miniaturisation stage, before completely dying. However for the hair follicle to die completely it takes a long time and some research around stem cells in the hair growing areas point to the fact that even after hair follicle does effectively die (i.e. it does not produce any type of hair, including vellus) – some stem cells can create new hair follicles.
For now, it is important to remember, that just because there is no visible hair – it does not mean that hair follicle is dead. Oftentimes even on bald-as-a-knee heads, there is some peach fuzz that points to the fact that the follicles aren’t dead, they are just in a different stage however, going through hair follicle minitiarrisation stage as a vellus hair.
What is a dead hair follicle?
Dead hair follicle is the one that no longer can grow hair. So it is important at the miniaturisation stage to know that once hair follicle is entering leads to reduction in blood supply. Although it is often not the lack of blood flow that leads to baldness, especially in males, but rather it is the result of it. The lack of appropriate blood circulation worsens and speeds up the hair loss, since the root no longer receives oxygen and other nutrients normally delivered by blood vessels connected to hair via a nipple-like extension, known as derma papilla. Therefore this lack of nutrition leads to a catch-22 process of hair miniaturisation and ultimately its death.
Stem cells and hair follicle formation: hair follicle re-birth
Aside from the differentiation between vellus hair and terminal hair, there is a number of stem cells present in scalp. Those stem cells need to transition to “progenitor” stage before leading to hair growth. You can think about progenitor cells not entirely devoid of purpose, like stem cells, but rather those which already leaning towards a target cell. Interestingly, in balding men, scientists observed the same amount of stem cells in the balding areas as in the non-balding areas, though in the non-balding areas there was a greater number of activated progenitor cells.
Bottom line is hair thinning and hair loss treatments are most efficient in the early stages of hair loss – when you just start noticing hair thinning and some smaller, often transparent vellus hair taking its place. It is much harder to revive a dead hair follicle and stimulate formation of progenitor cells – than the one which is still operating.