The appearance of a small, often white or translucent, bulb at the end of a plucked hair strand can be a surprising sight. This mass is not the entire hair follicle, which is the permanent structure anchored deep within the skin. What has been removed is the hair root, specifically the hair bulb, the base of the growing hair shaft. The presence of this bulb indicates the hair was forcibly removed, bringing with it the living cellular tissue that surrounds the root. This living tissue, known as the root sheath or follicular tag, distinguishes a plucked hair from one that has fallen out naturally.
The Hair Growth Cycle and Root Structure
Hair production occurs within the follicle, a complex structure that cycles through periods of growth and rest. At the base of the follicle is the hair bulb, which cups the dermal papilla, a structure containing the blood vessels that supply oxygen and nutrients. Above the papilla is the hair matrix, a region of rapidly dividing cells that produce the hair shaft itself.
The active growth period is the Anagen phase, which lasts several years for scalp hair. During this phase, the bulb is large and actively creating new hair cells. Because the hair is firmly anchored and the matrix cells are dividing quickly, forcibly removing an Anagen hair often results in the bulb and a sheath of surrounding tissue coming out with the strand.
The growth cycle transitions into the Catagen phase, a short period lasting only a few weeks where the follicle shrinks and the bulb begins to detach from the dermal papilla. This is followed by the Telogen phase, a resting period that can last a few months, where the hair is no longer growing. The bulb tissue at this stage becomes dry, hard, and forms a distinct club shape, preparing the hair for natural release.
Plucked Hair Versus Shed Hair
The appearance of the root end provides a clear visual distinction between a hair that was forcibly removed and one that shed naturally. A hair that sheds naturally has completed the Telogen phase, resulting in a smooth, unpigmented, club-shaped structure at the root. This club end is small and dry because the hair matrix stopped producing cells and the follicle shrank before the hair was released.
In contrast, a hair that has been plucked or pulled out prematurely often retains a significant portion of its root structure, particularly if it was still in the Anagen phase. This forcibly removed hair will have a large, often dark, bulbous end. A key characteristic is the presence of the follicular tag, a translucent or white tissue clinging to the base of the hair shaft.
The follicular tag is composed of cells from the inner and outer root sheath, which were ripped from the follicle lining during the forceful removal. This physical damage at the root end is evidence that the hair was extracted against its natural cycle. The size and shape of the bulb can indicate the amount of force used, as hairs in early Anagen are more deeply anchored and require greater force to remove.
Information Revealed by the Hair Bulb
The cellular material present on a plucked hair bulb transforms the hair strand from a simple protein filament into a valuable biological sample. The hair shaft itself is primarily composed of dead keratinized cells and contains only mitochondrial DNA, which is inherited solely from the mother and is not unique enough for individual identification.
The living cells of the follicular tag, however, contain the cell nucleus. This nucleus houses the individual’s unique nuclear DNA, the genetic material used in forensic science and personal identification. Because a plucked hair retains this nuclear DNA source, it is far more informative than a naturally shed hair that lacks the follicular tag.
Investigators can analyze the bulb’s appearance to determine the hair’s growth phase at the time of removal. A large, actively growing bulb suggests the hair was forcibly extracted during the Anagen phase, which could indicate a violent event. Conversely, a club-shaped bulb confirms the hair was in the resting Telogen phase, suggesting it fell out with minimal force. This information is valuable for forensic analysis and for diagnosing certain types of hair loss, where the ratio of Anagen to Telogen hairs can indicate a health issue.