Armpit hairs often appear to grow in pairs because they are Pili Multigemini hairs, meaning multiple hairs originate from a single follicle.
Understanding Pili Multigemini
These are not typical single-shaft hairs. Instead, they grow from a follicle with more than one dermal papilla. Here's a breakdown:
What are Dermal Papilla?
- Dermal papilla are structures located at the base of each hair follicle that regulate hair growth.
- Normally, a single follicle has one dermal papilla, resulting in one hair.
- In Pili Multigemini, a single follicle contains two or more dermal papilla, leading to multiple hairs sprouting from the same opening.
The Mechanism of Paired Growth
- Multiple Dermal Papilla: The presence of multiple dermal papilla within one follicle is the primary reason for multiple hairs emerging from what appears to be a single pore.
- Shared Follicle Opening: Although multiple hair shafts are produced, they often exit through the same follicle opening on the skin's surface, causing them to appear paired or clustered.
How This Relates to Armpit Hair
Armpit hair, in particular, is prone to this phenomenon due to the follicle structure in this area. It's not uncommon to find several hairs emerging closely together, sometimes looking like two hairs from the same point.
Treatment Considerations
- Identify Dominant Hair: When treating Pili Multigemini hairs, it's key to locate the most prominent hair.
- Targeted Treatment: Using a current on this hair may affect the other hairs, because they all originate from the same follicle. This is helpful during electrolysis or other hair removal methods.
Summary
| Term | Definition |
|---|---|
| Pili Multigemini | Hairs that grow in multiples (typically pairs) from a single follicle due to the presence of multiple dermal papillae. |
| Dermal Papilla | Structures within the follicle that regulate hair growth and determine the number of hairs produced. |
Ultimately, the appearance of paired armpit hair is due to the unique structure of certain hair follicles containing multiple dermal papilla, causing multiple hairs to emerge from a single pore opening.
