Hair structure: what are the dermal papillae used for?

Dermal papillae, although tiny and often overlooked, are crucial components of hair structure. Nestled at the heart of the hair follicle, they play a decisive role in hair growth and health. These structures supply the hair with essential nutrients and signal the start of new growth phases. Optimal functioning is essential for strong, healthy hair. Find out all you need to know about the dermal papilla.

What is the dermal papilla?

Located at the base of the hair follicle, the dermal papilla plays an essential role in hair growth. It is rich in microscopic blood vessels that supply oxygen and essential nutrients to the hair cells.

In addition to its nutritive function, the dermal papilla contains receptors for the molecular signals that regulate the growth and the hair life cycle. It is the biological engine that supports and stimulates the constant production of new hair, representing a vital element for hair regeneration.

How is the dermal papilla structured?

The dermal papilla is a conical or rounded intradermal structure located at the base of the hair follicle. It is mainly made up of connective cells and a rich capillary network that provides a direct supply of blood, and therefore oxygen and nutrients, to the follicle's growing cells. This vascularisation plays a fundamental role in hair growth, providing the elements necessary for the synthesis of keratin which is the main protein in hair.

The cells that make up the papilla are also involved in molecular signalling with the cells of the hair follicle. They react to various biochemical signals, such as hormones and growth factors, which regulate cell proliferation, the hair growth phase and the start of the resting phase. This complex interaction between papilla cells and follicle cells is essential for maintaining the hair cycle.

The dermal papilla is also responsible for the induction and maintenance of hair follicles, and is involved in hair repair and regeneration. So any damage to the papilla can lead to dysfunction in hair growth, underlining its importance in hair health.

How do dermal papillae influence the life cycle of a hair?

Dermal papillae have a significant impact on the life cycle of the hair by modulating the different phases of growth. They communicate with the cells of the hair follicle to trigger and regulate the anagen, catagen and telogen phases:

• The anagen phase: This is the growth phase. The dermal papilla actively supplies the follicle with nutrients, supporting intense hair growth. The signals emitted by the papilla stimulate the follicle's stem cells, triggering the production of new hair cells.

• The catagen phase: During this transitional phase, interactions between the papilla and the follicle diminish, leading to a reduction in cellular activity. The papilla retracts and the hair follicle gradually detaches, leading to the resting phase.

• Telogen phase : During this resting phase, the hair no longer grows, and the papilla, although less active, remains in place under the follicle waiting to signal a new cycle. The old hair shaft remains in the follicle until it is ejected or replaced by a new hair.

Dermal papillae do more than simply nourish the hair; they are active regulators of the hair cycle, essential for hair growth, transition and renewal.

What impact do hormones have on the activity of dermal papillae?

Hormones have a considerable influence on the activity of the dermal papillae, directly affecting hair growth and health. Androgens, such as testosterone and dihydrotestosterone (DHT), can shorten the anagen phase, reducing hair growth time and potentially leading to thinning and male pattern baldness. In women, oestrogen tends to prolong the anagen phase, promoting longer, denser hair growth.

Hormonal changes, such as those occurring during pregnancy, the menopause, or due to medical conditions such as polycystic ovary syndrome (PCOS), can alter hair density and texture through their effects on the papillae. For example, an increase in hormones during pregnancy can lead to thicker hair, while a drop in hormone levels post-partum can cause temporary hair loss.

Thyroid hormones also play a vital role in modulating the absorption of nutrients and the metabolic energy required for hair growth. An imbalance in these hormones can lead to dry or greasy hair, slow growth or even hair loss.

Dermal papillae act as mediators between hormonal signals and hair health, making hormonal balance essential for maintaining healthy hair.

Which hair problems are directly linked to dysfunction of the dermal papillae?

Dysfunction of the dermal papillae can lead to various capillary problems. The hair loss or alopecia, is often linked to papillae that are not functioning properly, whether due to hormonal imbalances, stress or nutritional deficiencies. 

Papillae can also be affected by autoimmune conditions, such as alopecia, that disrupt hair growth. 

The health of the papillae also influences hair density and thickness. As a result, a hair diagnosis is essential to determine the condition of the papillae and establish a personalised treatment plan.

Dermal papillae: the importance of capillary diagnosis

Performing a hair diagnosis is crucial for assessing the health of the dermal papillae. This process can identify potential causes of papillae dysfunction, such as genetic factors or environmental influences. 

Once a diagnosis has been made, targeted treatments can be offered to stimulate the function of the papillae and encourage healthy hair growth. Treatments may then include dietary changes or supplements to correct these imbalances and improve the overall condition of the hair.

Dermal papillae are at the heart of hair vitality, orchestrating hair growth and renewal. Their good health is essential for maintaining dense, strong hair, and their role in the hair's life cycle highlights the importance of appropriate care and treatments to preserve hair's shine and strength.